Inside America's Secret War with ISIS

U.S.-backed forces are about to seize Raqqa – the capital of the most wanted terrorist group on earth – so why won't the government talk about it?

A U.S. Marine deployed in northern Syria, March 2017 Credit: Lance Cpl. Zachery Laning/U.S. MARINE CORPS

An hour before dawn on a rooftop in Raqqa, you can see the Milky Way. The Islamic State's embattled capital in Syria, once home to hundreds of thousands of people, has been bombed back into darkness, but from the city center comes the trancelike recitation of the call to prayer. A sudden flash of red light illuminates the skyline, and a rumbling like distant thunder rolls over the rooftops. As soon as it subsides, the reading of scripture resumes, until it is again silenced by the flash and thud of an American bomb.

Since 2013, when ISIS fighters took control of the city, Raqqa has been the most violent place in the world, a no-go zone where medieval punishments like beheading and crucifixion are meted out in the streets and diseases like polio and black fever run rampant. According to a recent Web post by the only remaining outfit of citizen-journalists, "Hundreds of civilians have been killed and wounded during the past few weeks alongside massive destruction to the city's infrastructure, residential areas, and life-sustaining utilities." The United Nations says there is "no worse place on Earth."

Earlier this year, the tempo of the airstrikes reached a devastating crescendo in preparation for a U.S.-backed ground invasion. On June 6th, the Syrian Democratic Forces, or SDF, a coalition of mostly Kurdish militias, supported by American air power, attacked from the east and west, making rapid gains for 10 days, seizing an old army base, the ruins of an ancient fortress, a sugar plant, and most of the suburbs and markets on the industrial outskirts, but progress slowed once they hit dense urban terrain. ISIS has had years to prepare a network of trenches and tunnels in Raqqa and is determined to hold out as long as possible, as it did in Mosul, in neighboring Iraq, where American-backed Iraqi forces battled for eight months before declaring victory.

For the approximately 4,000 ISIS fighters holed up in Raqqa – many of them foreign-born volunteers – there is no exit. The Euphrates River limits Raqqa on the south, and all the bridges have been destroyed. The SDF controls the countryside to the north, and is now divided into two forces, trying to pinch ISIS into the center of Raqqa and kill them all. "Any foreign fighter who is here," the top American liaison to the SDF, Brett McGurk, told reporters, "they're going to die in Raqqa."

Embedded with the SDF are teams of American soldiers, about whom very little is known. The U.S. military's presence in Syria has grown exponentially since 2014, when the first elite commandos arrived to advise the nascent SDF. Today, there are some 14 U.S. military bases on Syrian soil. The troops on the ground include personnel from the Army, Navy, Air Force and Marine Corps, but the government won't say exactly how many, where they're located, what precisely they're doing or how long they'll stay. A few have died and a good deal more have been injured in combat, but like almost everything else about the U.S. presence in Syria, the number of wounded is classified. Despite the scale of the operation, the Pentagon insists on black-ops secrecy, refusing to embed reporters, and channeling all information through spokesmen in Baghdad. Turkey and Iraq have imposed a blockade on Syria that prevents most independent reporters from getting anywhere near American forces on the battlefield, and soldiers are apparently under orders not to answer questions or allow themselves to be photographed.

After being smuggled across the Tigris River into Syria by inflatable boat on June 23rd, I link up with a pair of Kurdish journalists who drive me the rest of the way to Raqqa. North of the city we pass a refugee camp for the tens of thousands of people who have fled the fighting. Tents along the highway are patched together from canvas sacks, plastic tarpaulins, reed mats and animal hides. Sad scenes of wartime suffering flit past our van's window: widows dressed in black, begging for food; a crippled man in a wheelchair, carving a ragged red carcass; a cow drinking from an open sewer. Driving into Raqqa, past ISIS graffiti on battle-mangled storefronts, the streets look like they've been hit by a meteor shower, pocked with craters and riddled with bullet holes. There is not one civilian to be seen out of doors.

We are cruising through a recently liberated neighborhood one morning when we spot an American convoy: three hulking armored vehicles known as MRAPs, built to withstand mine blasts. The tail vehicle is a Toyota Hilux, an escort truck driven by a couple of Kurdish soldiers. The convoy turns onto a rutted dirt road and we follow at a distance, our battered old van's sliding door rattling the whole way. The Americans move through a trash-strewn pine grove, their 30,000-pound vehicles raising a cloud of fine dust obscuring all but their red taillights and lashing antennae.

Our van emerges from the dumping ground onto a dirt road, but the convoy's escort truck cuts us off. My Kurdish colleagues hail the Kurdish soldier in the driver's seat and flash press credentials, pretending to be lost. While they talk, I'm in the back seat, behind a tinted window, continuing to film the armored vehicles as they file into the courtyard of an abandoned building. But the last armored vehicle stops short. Its computerized turret rotates and fixes on the van in a quick, insect-like motion. Beneath the barrel of its gun there is a video camera, an infrared sensor and a laser range finder, a cluster of dark lenses that looks like a spider's eyes. I realize the thing can see through the van door: a thermal image of me in the back seat, green and yellow and red, my heart and brain glowing hottest pink. The way I'm half-kneeling on the floor, holding up a cellphone, I could be mistaken for an enemy triggerman.

I experience a wash of fear and – unexpectedly – humiliation, the shame of defenselessness. As a veteran of the Iraq War, I know what it's like to be the one looking through the sights. Now, for the first time, I have some idea of what it's like to be a civilian – a "local national," in military parlance – in one of the countries the U.S. has invaded: Afghanistan, Iraq and now, little by little, largely in secret, Syria.

On the east side of Raqqa, in a wrecked neighborhood called Sina'a, I meet a platoon of Kurdish SDF inhabiting a two-story- house littered with water bottles and soda cans, fly-swarmed food tins, candy wrappers and stale bread. There are countless cigarette butts in the hallways, and cooking fires have been made on the floor. There's no running water, but that hasn't stopped anyone from using the toilets. The 30-odd fighters living here the past two weeks are mostly teenagers, boys and girls in high spirits, chatting and clowning around, sipping energy drinks, smoking cigarettes and thumbing their cellphones, showing each other clips of combat and music videos. They wear the U.S. Army-inspired pixilated camouflage uniform of the SDF, some with sneakers and some with sandals and socks, and they sport a comical array of random headgear: kaffiyehs and do-rags, bucket hats, a newsboy, even a trilby. None of them have body armor or helmets.

Their commander is Tekoshin Derik, a 19-year-old woman with green eyes and a streak of purple in her hair. The lieutenant at her side looks even younger, maybe 17, with two blond braids under a floppy patrol cap. I know the Syrian Kurds are radically feminist, but I can't help but wonder how someone Derik's age came to be in charge of an infantry platoon. "Age has nothing to do with it," she says, firing up a cigarette with cocky adolescent verve. "It's a matter of will to stand against the enemy."

The Kurds were not America's first choice for an ally in Syria. The bulk of the SDF are young Syrian nationals like these, but their most experienced commanders, the ones who first organized the resistance to ISIS, are veterans of a Marxist-Leninist war for Kurdish independence in southeastern Turkey, a NATO member and ally of the United States. The Kurds are no longer communists but adhere to a far-left, anarcho-feminist ideology closer to Occupy Wall Street than to anything in the Middle East. Their autonomy movement, known as the Rojava Revolution, has attracted leftist volunteers from six continents, but Turkey, under its increasingly authoritarian Islamist president, Recep Tayyip Erdoan, is obsessed with preventing them from establishing an independent territory on its southern border. When ISIS attacked the Kurds, whom they consider unbelievers, Turkey secretly sided with ISIS as the enemy of its enemy.

The U.S. first intervened in Syria around the same time, on the other side of the fight, hitting ISIS with airstrikes during the 2014 siege of Kobanî, in order to avert what looked like imminent genocide. As the Kurds started rolling back ISIS territory, the impromptu Kurdish-American alliance evolved into a more formal coalition, antagonizing the Turks, who consider any armed Kurd a terrorist. In order to placate Turkey, and not to be seen as backing a single ethnicity in a sectarian war, the U.S. helped organize the SDF, which also includes Arab, Assyrian and Christian militias. Supported by American air power, the SDF slowly- swept across northern Syria, pushing ISIS back toward Raqqa one farm, one village, one town at a time. During this long slog, American soldiers took part in dozens of battles that went almost totally unreported in the U.S., including the seizure of Tabqa Dam in May, in which hundreds of American commandos fought, with support from Marine artillery and helicopter gunships. But those were mere skirmishes compared with a city the size of Raqqa.

I'm about to ask Derik what she was doing before the war, but I realize that was six years ago – she would have been a child. Instead, I ask what she'll do when the war is over. "This war will never end," she declares, waving away cigarette smoke, "and we will never stop fighting to defend our people."

We're sitting on a hideous plaid couch when a series of sharp explosions moves everyone away from the doors and windows. An ISIS drone, Derik tells me, is dropping grenades on the house's roof-mounted- machine gun. Everyone congregates in the central stairwell to wait out the bombardment. Tea is served. Another series of detonations slams the building, a mortar barrage this time. Derik gets on the radio, a sorry contraption with six D batteries taped together. There is confusion on the other end, garbled static. "Where are they firing from?" Derik says. After a pause, the boy's voice on the radio haltingly describes a location. "Well, then, friend," she says into the handset, "we better go get them."

Derik sends three fighters to join those already outside to attack the ISIS mortar position. Along with their weapons, they carry a case of bottled water and a sledgehammer. The girl with blond braids is among those chosen, and she slings her rifle on her back, hugs her female friends and shakes hands with the boys. On her way down the stairway she wipes tears from her eyes, but she's smiling.

Through a barred window in the stairwell, a row of grain silos about a mile away explodes under a volley of artillery. Billows of churning dirt bloom in the bleary midday heat. It's the Marine Corps, Derik says, using their howitzers to shell ISIS snipers on the silos. I ask her about the U.S. role in the fight. She mentions a joint command room but otherwise downplays the American presence – something I encounter with nearly every SDF commander. I can't tell if they are angling for greater support or are complicit in the U.S. military's efforts to minimize its activities in Syria. Among other things, Derik denies that American soldiers are engaged in direct combat. "On the front line, I haven't seen any Americans," she says. But as we're leaving, I notice a Humvee parked out back, right behind the house, half hidden under an arbor of grapevine. In the front seat are two Caucasian commandos. They stare at me, expressionless behind their sunglasses and beards. I go to snap a photo but our SDF escort puts his hand on my arm. "It's banned," he says, "and they will be angry."

ISIS has claimed responsibility for terror attacks that have killed more than 2,000 people in more than 20 countries since 2013. But the American coalition's fight in Syria is being waged outside any recognizable legal framework. Neither the United Nations Security Council nor the U.S. Congress, which has exclusive power to declare war under Article I of the Constitution, has authorized the use of force. There is a law on the books allowing the president to direct military action against anyone who "planned, authorized, committed or aided" the September 11th, 2001, attacks, a statute that has been used to justify- U.S. force in a half-dozen countries, but ISIS didn't exist in 2001. It is the spawn of the Iraq insurgency; its head, Abu Bakr al-Baghdadi, was a prisoner in Abu Ghraib. Al Qaeda fights in Syria as Jabhat al-Nusra, and has been an enemy of ISIS since 2014.

In August 2013, President Obama did seek congressional approval to bomb the regime of Bashar al-Assad, after the Syrian dictator used sarin gas against his own citizens as part of the country's ongoing civil war. But the resolution, introduced in the Senate, never got a floor vote. "If members of Congress were forced to take an affirmative stance in favor of intervention, for many of them that would be a tough vote to cast, given what the country has been through in Iraq and Afghanistan," says Jason Brownlee, a professor at the University of Texas at Austin who studies U.S. interventions in the Middle East. Aside from the occasional protest from isolationist lawmakers like Sen. Rand Paul, Congress simply hands over the money as the Pentagon requests it: $14.6 billion so far, with another $14 billion set aside for 2017. "If you actually started debating the perpetual state of conflict post-9/11, you would immediately run into the question of what the boundaries should be," says Brownlee. "The hawks don't want to put any constraints down on paper, and why ask permission when nobody's going to stop you?"

After ISIS seized control of a nation-size territory in the summer of 2014, Obama didn't bother to seek congressional approval for Operation Inherent Resolve, the Pentagon's anti-ISIS campaign in Iraq and Syria. Though Obama had said on 16 occasions that there would be no "boots on the ground" in Syria, he sent 50 elite commandos to advise the SDF in October 2015, and another 250 six months later. The first American combat death occurred in November 2016, when a naval bomb-disposal technician was killed by an explosive device outside Ayn Issa. By December 2016, the number of commandos had increased to 500.

I was reporting in Syria at the time, and it was clear that the SDF intended to assault Raqqa. Along a muddy 300-mile front, I saw "Rakka em hatin" – Kurdish for "Raqqa, we're coming" – spray-painted- on demolished houses and abandoned cars. But if the U.S. were to give the SDF the armored vehicles and anti-tank weapons they needed, Turkey would have been liable to retaliate in unpredictable ways. Obama's top generals were all for it, Turkey be damned, but civilian officials and diplomats were more skeptical. After seven months of internal debate, Obama decided to approve the Pentagon's plan, which also specified deploying hundreds of Marine Corps artillerymen to the outskirts of Raqqa. But by then, Obama's term in office was effectively over.

The Obama team passed the plan to the incoming administration, which included Michael Flynn, Donald Trump's first pick for national security adviser. As he was later forced to admit, Flynn had received a half-million dollars to do lobbying work on behalf of the Turkish government, and he spiked the plan to arm the Kurds even before Trump took office. (A month later, Flynn was forced to resign over undisclosed contacts with Russia.)

Trump is on record saying, "We should stay the hell out of Syria," and criticized Obama for using military force without congressional authorization. During the campaign, Trump also said he had a "secret plan" to "crush" ISIS. But on February 27th, Secretary of Defense James Mattis submitted a proposal that most analysts believe was a doubling-down on the Obama strategy. In April, Trump quietly signed an order allowing the Obama plan to proceed without obvious modifications.

Within 24 hours, weapons shipments began. An SDF source sent me a video of Kurdish militiamen standing alongside a road, cheering as a convoy of flatbed trailers loaded with Humvees, armored vehicles, heavy machine guns and mortar systems rolled into Syria, accompanied by U.S. Marines. The Washington Post called the deployment a "new escalation" because Marines are ordinary grunts, not elite commandos. But back in November, I met with a handful of left-wing volunteers, Americans and Europeans who had joined the Kurds, and they reported fighting side-by-side with Marines in a battle for a town called Tal Saman. "They were wearing uniforms that said u.s. marines," says Tommy Mørk, a Danish volunteer. If true, it would mean the Marine Corps was in Syria months before the deployment of the 11th Marine Expeditionary Unit officially took place.

There's also reason to believe the actual number of troops on the ground is higher than the Pentagon has disclosed. U.S. Army Col. Ryan Dillon, a spokesman for Operation Inherent Resolve, told me that military regulations cap the number of personnel who can be in a given country at any time; for Syria, that number is exactly 503. When I explained my tally of publicly disclosed deployments, which added up to about 1,000 soldiers and Marines, he clarified that the cap doesn't include those deployed on a "non-enduring basis," which the Pentagon interprets as anything under 180 days. So, in theory, there could be any number of troops in Syria, thousands or even tens of thousands, and military spokesmen would still be telling reporters the number is 503.

The rules of engagement have also undergone a quiet revision. In the beginning, the military said American soldiers were in Syria to "advise and assist" Kurdish forces. Sometime in 2016, that morphed into "advise, assist and accompany," a subtle change that allowed U.S. troops out of headquarters and onto the battlefield. It's moot in any case. The Trump administration recently announced that it would no longer disclose any information on the "capabilities, force numbers, locations, or movement of forces in or out of" Syria. The picture, already blurry, went completely black.

Touring the towns and villages north and west of Raqqa, where the U.S. military is concentrated, I learn to recognize an American gun truck from a distance: roof rack piled with boxes of ammo and rations, a rocket launcher slung behind the cab, a spare tire on the tailgate, a tow hook on the bumper and a powerful-looking antenna. Their white Toyota Hiluxes and Land Cruisers are always covered in dried mud; on close inspection, though, you can see it's been deliberately- applied with a sponge, maybe for camouflage. They also seem to have a thing for fuzzy dice. To judge from their mismatched uniforms and scruffy beards – status symbols not permitted to common soldiers – they are mostly Army Rangers, Green Berets and Navy SEALs.

After 16 years of continuous warfare, the military has learned to keep casualties low by keeping personnel inside vehicles. (Of the dozens of Americans I saw in Syria, not one had his boots literally on the ground.) Forty American servicemen have died while deployed on Operation Inherent Resolve, according to the Department of Defense, three of them in Syria. The Pentagon won't say how many more have been injured, citing vague "operational security" and "privacy" concerns, but in response to a Military Times investigation in January, officials quietly acknowledged the number is on the rise.

In July, in what appeared to be a deliberate stunt to spite the U.S., Turkey's state-run news agency published a map revealing the locations of 10 American bases in Syria. I personally observed two bases in the northern Kurdish-held part of the country that were not on the Turkish map. There are two more American bases in the southeastern desert known as the Badia: a commando garrison with a long-range rocket system at the Tanf border crossing, and a patrol base at a place called Zakf. That adds up to at least 14 U.S. bases, a number Dillon declined to confirm or deny.

On one rare occasion, the military allowed a few hand-picked journalists to take a guided tour of a base outside Kobanî. I spoke with one of the reporters afterward, who said there were "hundreds" of American soldiers on the base, which he described as "dusty" and "huge," taking five minutes to drive clear across. The soldiers were busy building barracks, he said, and had already built an ammo dump capable of storing 80,000 pounds of munitions. He was most impressed by the landing strip, which was paved and sunk below grade, so that to an observer on the ground, planes seemed to disappear after landing.

One base I pass on the road to Raqqa is built around a concrete plant, a massive facility with industrial structures 20 stories tall. Locals drinking soda pop in front of a nearby store show me a cellphone video of what looks like missiles launching from within the compound. That reminds me of an obscure Air Force notice I'd read back in March, announcing the death of Staff Sgt. Austin Bieren, of Umatilla, Oregon. Bieren, who was 25 years old and an active outdoorsman, died of "suspected natural causes" at an undisclosed location in "northern Syria." He had been assigned to the 21st Space Wing, a unit normally tasked with operating missile warning systems and space-object detection.

The concrete plant is surrounded by a perimeter of dirt berms and blast walls topped with razor wire. At the entrance, behind a row of heat-stricken pine trees, I can make out two Americans in a guard tower. "You cannot approach," a local man tells me. And what would happen if I did? "They will shoot you," he says. What if I called to them in English and show them my passport? The man holds up a hand and says, "They will not even ask questions."

On my fifth day in Syria, i visit a first-aid station on the eastern edge of Raqqa, where explosions have been pounding since sunrise. Midmorning, a truck pulls up and six SDF soldiers pile out, limping and bleeding. Their position got nailed by an ISIS mortar, I later learn, a direct hit. One of them is unconscious and has to be carried out in a blood-soaked blanket. The medics help the other wounded men lie down. The aid station is a converted storefront, very small, and there is only one stretcher – a coffee table, really – which goes to a soldier whose legs have been cut up by shrapnel. The others lie on the floor or the sidewalk outside, groaning in pain, crying out for water. The SDF doctor gets to work, giving injections and cutting off uniforms and squirting disinfectant into wounds. Blood and iodine smear the linoleum. Strips of clothing and dirty bandages pile up in a hamper. Amid the chaos, a soldier holding a compress to his shoulder starts to sing.

The doctor has only had time to treat three of the wounded when a Humvee pulls up. In the front seat, behind thick bulletproof glass, I can see two Americans wearing wraparound shades, but they don't get out of the vehicle. An SDF fighter with long hair and a bewildered look in his eyes stumbles from the back seat supporting a buddy, who's been shot in the side by a sniper. They lay him down on the coffee table as the doctor collects his forceps and scissors. He cuts away a bit of pink flesh and flings it onto the floor, where the flies are feasting, then takes a flexible plastic tube and inserts it deep into the wound, making a gruesome squelching sound. It's an operation to relieve pneumothorax, a condition in which lung-crushing pressure builds up in the chest cavity after it's been penetrated by a bullet.

Afterward, I talk to the doctor, a Turkish--speaking Kurd who looks like Vladimir Putin. He tells me the medical situation is very bad. The lack of electricity is a major problem. The pneumothorax operation, for instance, should not be performed in an environment hotter than 41 degrees, and it's 115 degrees in the shade. He tells me that medical supplies are extremely inadequate, that the U.S. military has provided nothing. He says there is an American hospital where they can send the most serious cases, but it's an hour's drive over bad roads.

According to Dillon, American medical personnel are currently in-country, treating injured SDF along with U.S. troops, and these trauma teams are in the process of being moved closer to the front line, along with refrigeration units to preserve blood. But today the doctor performs one operation after another without any assistance, working silently in the extreme heat, beads of sweat dribbling from the tip of his nose. In the distance, the dismal drumbeat of artillery is unrelenting. He ends up operating on 12 men in a span of 90 minutes, all of whom survive, with one possible exception.

The soldier laid on the sidewalk in a blanket is the most badly injured. He looks to have taken the brunt of the mortar blast to his face and is unresponsive. His thin stomach rises and falls with the help of a hand-pumped resuscitator. When they load him up in the ambulance, on the threshold of death, there are three reporters recording what will likely be his last moments of life, including me. "It's not good to film," my translator, Jan, says, covering his eyes and walking away.

Between trips to the front line, I visit Manbij, a mixed city of Kurds and Arabs just west of the Euphrates. The summer 2016 operation to drive ISIS out of here was the first battle for a major Syrian city that American forces took part in. It was a brutal fight, and piles of rubble still block the sidewalks, trash is heaped around broken lampposts, and the smell of death wafts off the canal in the center of town. But there are signs of renewal: the noise of jackhammers and drills; watermelons for sale; pairs of freshly barbered young men, walking hand-in-hand; a wedding party, preceded by flower girls.

At a guarded government compound, I meet a Kurdish commander called Adnan Amjad, chief of the Manbij Military Council, which was recently cobbled together to maintain security. "During the liberation we had very good coordination with the U.S. military," says Amjad, an intimidating man with short gray hair and a pistol on his belt. The U.S. set up a joint command center and provided guns, trucks, ammunition and GPS devices to direct airstrikes, he says. More than 100 U.S. troops are now stationed at a couple of bases in the countryside, chiefly to deter attacks by Turkey, which invaded a pocket of northern Syria to block the SDF from advancing any farther west. Throughout the interview, Amjad rails against the Turkish government, his aides frequently chiming in to reinforce his arguments or offer further proof of alleged Turkish collusion with ISIS. "The international community and the USA need to stop Turkey from threatening us," says one of Amjad's aides. "If we were not fighting ISIS, they would be in America."

In an e-mailed statement, the Turkish embassy flatly denied supporting ISIS, but there is little doubt that Turkey is working to frustrate the Kurdish-American alliance. The Turkish military often bombs and shells SDF positions around Manbij, despite the presence of U.S. forces. In order to deter further fighting, the Americans have taken to patrolling the line between the Turks and Kurds in armored vehicles flying full-size American flags, a tactic that risks a direct Turkish-American clash. Turkey already killed a young American named Michael Israel, a leftist volunteer, in a November 2016 airstrike. On June 26th, Turkey moved tanks and artillery to the Tal Abyad border crossing, threatening the SDF's rear guard. In response, six U.S. Army Rangers rode up in light gun trucks. According to a local journalist, Turkish border guards fired on the Rangers at 400 yards. It was just a show of force, but the "overt patrols" outside Manbij repeatedly came under direct attack in August. On August 29th, the U.S. coalition said it had submitted an official protest to the government of Turkey. On the same day, the SDF announced that Amjad had died fighting ISIS in Raqqa; a conservative Turkish newspaper loyal to Erdoan celebrated the news, calling Amjad a terrorist.

Syria is an extraordinarily complex battlefield, crowded with international proxy conflicts: Sunni versus Shia; Iran versus Saudi Arabia; Turkey versus the Kurds; and now, the U.S. versus Russia. At the invitation of Assad, Russia has several thousand soldiers and mercenaries in Syria who are helping him fight the Free Syrian Army. That battle is proceeding apart from the Kurdish offensive against ISIS, but overlap is inevitable. With the regime advancing on ISIS from the south, Russian and American troops are essentially on opposite ends of a shooting range. Russian convoys have been photographed here in Manbij, and it's said to be the first time since World War II that Russian and American soldiers have operated in the same city.

Russia and the U.S. maintain back-channel- communications to avoid an accidental clash, but the same can't be said for Iran, which has deployed thousands of sectarian combatants to prop up the Syrian regime. Iranian agents have dominated Iraq since the end of the U.S. occupation, and a foothold in Syria could create a corridor all the way to Iranian-funded Hezbollah in Lebanon, which would give Iran an unimpeded land bridge from Tehran to the Mediterranean. "An ancient scheme," a U.S.-backed rebel commander recently told Al-Monitor. "Yet we are lying in wait." An American garrison at the Tanf border crossing, where a handful of shooting incidents have already occurred, stands in the way of Iran controlling the highway from Baghdad to Damascus. In May, American forces called down an airstrike on a column of Iranian militiamen speeding toward them, and twice in June they shot down Iranian drones, one of which had fired on U.S. forces patrolling the desert.

On the way back from Manbij, we pass a U.S. base whose location has never been disclosed. The terrain is hot and dry, with low hills of bleached grass and crispy nettles. A flock of sheep moves across the setting sun in a haze of dust. The base, enclosed by high walls and razor wire, covers several acres on the side of a two-lane road. The American soldier on guard duty sits up straight, angling his rifle in the direction of our taxi. On the roof of the building are two Americans with buzzed heads, one black, one white, both stripped to the waist. The black guy lights a cigarette and leans over the parapet. The white guy is red with sunburn and rubs his beer belly, taking in the purple dusk. They don't look like they're going anywhere anytime soon. 

On June 29th, we travel to the western front of Raqqa, where the most intense clashes have taken place. Here the urban landscape has an eerie, deserted feel. The streets are wider, the buildings bigger and clustered in apartment blocks, making it hard to keep track of the shifting line between small teams of SDF and ISIS, both of which seem to have far fewer fighters than they claim. ISIS is an especially ghostly- presence, befitting its origins in covert insurgency. Its top leaders, including -al-Baghdadi and his largely Iraqi, ex-Baathist lieutenants, are believed to have decamped down the Euphrates River valley. The die-hards left behind have to rely on surprise tactics: strike-and-fade attacks and martyrdom operations, especially suicide car bombs.

We're walking up the middle of a street strewn with piles of rubble and downed power lines, following a guide the SDF has assigned to us, a Kurdish soldier of about 20. Rifle shots boom from the charred tenements, but when I look up, all I see are ragged curtains drifting in empty windows. I ask our guide if he knows who is doing the shooting, but he's preoccupied, squinting up with a hand shading his eyes. He says there's a drone up there. It's the middle of a hot day, but a crescent moon is visible in the sky. I don't see any drones but I do hear a faint noise, like a mosquito whining in your ear. We duck into the entryway of a nearby building.

ISIS doesn't have an air force, but they've learned to rig cheap, off-the-shelf quadcopters with improvised switches capable of dropping 40-millimeter grenades. Every SDF commander I speak to says that drones are their biggest problem. They're nearly impossible to spot, and their digital cameras can search out high-value targets, like American commandos. Having introduced drones into modern warfare, the U.S. military is now scrambling to defend against them. Prototype drone-jamming radio-rifles have appeared on the battlefield, and a Dutch journalist in Kobanî tells me that he unpacked his Chinese-manufactured camera-drone to find that it had been factory-programmed not to function in Syria.

The building where we've taken cover smells like human shit. My eyes adjust to the darkness and I see there's a huge hole in the middle of the floor. Aside from drones, tunnels are the other big thing that SDF commanders worry about. Every square foot of Raqqa is under drone and satellite surveillance, watched by American airmen sitting in cubicles in Virginia, so ISIS digs entrances and exits to subterranean passageways inside buildings or in groves of trees. Its suicide attackers pop up behind SDF lines and detonate themselves or unload with a Kalashnikov till they're shot down. This tunnel is big enough to swallow a car. There is a rusty winch and tackle rigged above it, and the back rooms are so piled with excavated dirt that our heads graze the ceiling. I'm looking for augers or boring machines, but our guide tells me that ISIS dug this by hand, with shovels and picks. I'm skeptical but he just shrugs. "It's jihad," he says.

The drone moves off and we continue on our way, headed to an SDF position on the very front line. We clamber over piles of bulldozed gravel and walk between vacant buildings echoing with sniper fire. It seems like we're dangerously exposed but our guide doesn't seem to care, trudging ahead with his rifle dangling in one hand.

On the top floor of a three-story building we meet a squad of Arab SDF, six barefoot recruits from just-liberated parts of Raqqa province, hastily trained and armed with a handful of Chinese-made Kalashnikovs, no two of them alike. There have been reports of the SDF practicing conscription, rounding up youths and forcing them to fight ISIS. These boys have a spooked look in their eyes, and their words sound canned. "This is our first chance to fight back against ISIS," says Hilo Alguna, a 19-year-old with broken teeth and tattoos on one hand. "We are happy."

They pour us cups of sugary tea, using a pair of baby pants for a potholder, and show us around the building, which they recently took from ISIS. I haven't bathed in five days and think I might have fleas, but I'm still appalled by the filth of the place. Refuse is piled in the stairwell, and planks have been laid over broken glass and splintered furniture. There's a shelf of books that I'm afraid to touch, having heard too many stories of ISIS planting land mines in innocuous places. On one shelf is a blister pack of pseudoephedrine, which ISIS fighters pop to stay up for days at a time. In the back room, which has an open window, there is a pile of documents. An old illustrated Koran, written in Turkish and recovered from the wreckage, is offered as proof of the Turkey-ISIS nexus. I'm shown a "passport to paradise," a motivational booklet that ISIS distributes to its doomed fighters, authorizing them to enter heaven upon death. Flipping through the pages, I'm thinking about the symbolic potency of a passport in a country like Syria, when a rocket grenade explodes against the windowsill.

We stumble out of the room with ringing ears. My translator, Jan, scolds the Arab boys for not letting us know ISIS was so close, but they just stare at him. Our laconic guide is still in the room with the piles of documents, chips of concrete at his feet, when another rocket grenade explodes against the wall. He just wipes his nose with the back of his hand and looks away, as if contemptuous of the enemy's aim. The rest of us are packed in the stairwell. I ask the SDF if they're going to mount a counterattack. They hold a discussion among themselves, and decide to wait for the Americans to drop a bomb. They sit down around the teapot and light cigarettes.

There's no telling how long it will take the SDF to liberate Raqqa. The fighting could last months or more, but even then the U.S. involvement in Syria won't be over. Dillon has told me that U.S. forces will assist the SDF in pursuing ISIS farther down the Euphrates, and American officials have repeatedly declined to set a timeline for a withdrawal. For now, we can only hope the U.S. military won't repeat the same mistake made in Vietnam and Afghanistan and Iraq, a prolonged invasion fighting a local insurgency that thrives on war. We know how that story ends, or doesn't end.

After waiting nearly two hours, we decide to fall back before the shooting and shelling get any more intense. There's a plane flying slowly overhead, low enough for me to see that it's an American A-10, a sturdy old warplane that uses rotary cannons for close-range support of infantry. Like idiots, we stand there and watch as it slowly banks and turns, headed back in our direction. When it opens fire there's a long ragged burping sound and a puff of smoke from its spinning cannons. A hurricane of bullets rips into a stand of palm trees in front of a house a hundred yards away, raising a storm of swirling dust. Finally, our guide sees fit to run.