The Quagmire

One militant force, the Mahdi Army, recently stormed a peaceful picnic in Basra, where they ripped the blouse of a woman wearing Western garb. "We will send a picture to your parents," a gunman told her, "so they can see how you were dancing naked with men." The Mahdi, which battled U.S. forces during two major uprisings last year, is fiercely loyal to the charismatic and fanatical cleric Muqtada al-Sadr, the scion of a leading fundamentalist Shiite family. Al-Sadr's militia, hammered in last year's clashes, is quickly rebuilding with new recruits armed with machine guns, rocket launchers and rocket-propelled grenades. It now controls a big chunk of Basra, Iraq's only port and second-largest city, along with Kut, Amarah, Nasariyah and the huge eastern district of Baghdad known as Sadr City. In April, al-Sadr organized a rally of 300,000 people to demand that U.S. troops leave Iraq.

The Mahdi Army's main rival for power among the Shiites is the Badr Brigade, which has an estimated 20,000 men under arms. Badr is run by the Supreme Council for the Islamic Revolution in Iraq, which was founded by Ayatollah Khomeini in Iran and trained by his Revolutionary Guards. SCIRI's leaders still have close ties to Iran, even though many of its officials have been elected to the new Iraqi parliament. The hard-line group is powerful in Iraq's two holy cities, Najaf and Karbala, and controls another chunk of Basra.

Other Shiite forces include the Dawa Islamic Party, whose chieftain, Ibrahim al-Jaafari, is Iraq's new prime minister. Dawa was an underground terrorist organization in Iraq from the 1960s through the 1980s, and militants linked to the group attacked the U.S. and French embassies in Kuwait in 1983. While the State Department says it has no evidence to connect al-Jaafari himself to any terrorist acts, those who study the group suspect that Dawa also gets support from Iran. "They've been spreading money to everyone," says Juan Cole, an expert on Shiism at the University of Michigan.

The Sunnis: In central Iraq, millions of formerly dominant Sunnis opted out of the elections for the new government, which they see as being almost entirely in the hands of southern Shiites and northern Kurds. There are now several dozen Sunni organizations fighting the U.S. occupation, broadly divided into two camps: mainstream, secular Arab nationalists who served as military officers and Baath Party leaders under Saddam, and Islamist fundamentalists, including extremists associated with Abu Musab Zarqawi.

Most of the attacks on American forces -- the roadside IEDs, mortar strikes and full-scale assaults -- have been conducted by the mainstream resistance, who are intent on driving out the U.S. They have brought down helicopters, destroyed at least eighty of the Abrams tanks that are the mainstay of the U.S. occupation, and mounted large-scale actions involving scores of fighters, such as the April attacks on the Abu Ghraib prison and at Al Qaim near the Syrian border. In one recent incident, car bombs exploded simultaneously in front of and behind a U.S. convoy, which then came under intense fire from automatic weapons wielded by snipers inside abandoned buildings along the route.

The Islamist extremists, including partisans tied to Al Qaeda, mix attacks on U.S. and Iraqi troops with bloody suicide bombings against Shiites and other Iraqi civilians on pilgrimages and in mosques. According to intelligence sources, including U.S. military officers who travel frequently to Iraq, such attacks on civilians have fueled a split between the two camps. "There is a big gap between the mainstream resistance and the extremists," says a U.S. military officer, who added that the nationalists are debating how to create a political force to represent them, much as the Irish Republican Army had both military and political wings.