Shiite militias backed by Iran have ramped up attacks on U.S. troops in Iraq, making June the deadliest month in two years for American forces. The militiamen's goal is to prevent the U.S. military from extending its presence in the country past the end of this year.
Three separate militias have been involved in the attacks, particularly a small but deadly group known as the Hezbollah Brigades, believed to be funded and trained by Iran's elite Revolutionary Guard and its special operations wing, the Quds Force.
The militia attacks _ mainly in the Shiite heartland in southern Iraq _ raise the prospect of increased violence against Americans if a residual U.S. force remains in the country past 2011, a possibility being considered by the Baghdad government to help maintain a still fragile security.
They also point to the persistent efforts by Shiite-majority Iran, the United States' top regional rival, to influence Iraq after the Americans' exit.
In a statement targeted at the militias, Iraqi parliament Speaker Osama al-Nujaifi called Thursday on all groups to support the government in Baghdad if it ultimately decides to ask U.S. troops to stay.
In the latest American deaths, a senior U.S. official in Baghdad said Thursday that three U.S. troops were killed a day earlier when a huge rocket known as an IRAM struck a remote desert base just a few miles (kilometers) from the Iranian border in Iraq's southern Wasit province.
The deaths brought the monthly U.S. military toll to 15, nearly all of them of them from attacks suspected to have been planned by planned by Shiite militias. That's the highest number of military deaths in Iraq since June 2009, and the most combat-related deaths since June 2008. Since March 2003, 4,469 American troops have died in Iraq.
The IRAMs are a hallmark of Hezbollah Brigades, or Kataib Hezbollah, a militia that U.S. Maj. Gen. Jeffrey S. Buchanan, the military's top spokesman in Iraq, said is almost exclusively reliant on Iran.
The Hezbollah Brigades, which has links to the Lebanon-based Hezbollah, is solely focused on attacking U.S. troops and other American personnel and claimed responsibility for a June 6 rocket attack that killed five soldiers in Baghdad.
The force, estimated at about 1,000 fighters, receives unlimited funding from Iran, an Iraqi lawmaker familiar with militia operations said. Its militants are paid between $300 to $500 each month, said a senior Iraqi intelligence official. He described the militia as the most difficult for counterterror forces to penetrate because, like al-Qaida, operatives are segregated into cells that strictly kept apart.
The lawmaker and Iraqi official, along with several U.S. officials, spoke on condition of anonymity to discuss sensitive intelligence matters.
The new spate of attacks on U.S. troops began in mid-March, after the Obama administration started hinting it would prefer to see some American troops remain in Iraq into 2012 to help preserve the nation's shaky security and stave off Iranian influence. About 46,000 U.S. troops remain in Iraq, and those are supposed to leave by Dec. 31 under the terms of a 2008 security agreement between Washington and Baghdad.
Also involved in anti-U.S. attacks is the Promised Day Brigade, linked to anti-American cleric Muqtada al-Sadr and his Mahdi Army.
Al-Sadr holds considerable sway in Iraq's government, and U.S. officials believe the Promised Day Brigade _ which is five times the size of the Hezbollah Brigades _ poses more of a threat to Iraq's long-term stability than the other militias. Al-Sadr's political party holds 39 seats in parliament, and it was with his support that Prime Minister Nouri al-Maliki was able to keep his job for a second term after 2010 elections.
Al-Sadr disarmed his Mahdi Army after it was roundly defeated by U.S. and Iraqi forces in fierce 2008 battles in the southern port city of Basra. But he created the Promised Day Brigade to keep a militia on hand to "resist the occupier," a U.S. military intelligence official said.
The force gets hundreds of millions of dollars in financial assistance, including from Iran, a large number of sympathizers in Turkey and donations from around the Muslim world, a senior Mahdi Army commander said. It is also funded by the Sadrist political organization, to which every party lawmaker and minister donates about $5,000 a month.
Iran contributes far less to the Promised Day Brigade than it does to other militias, in part because al-Sadr has avoided allowing Tehran to wield as much control over the force, said the commander, who spoke on condition of anonymity to discuss the force's inner workings.
Though he lived in Iran for the last several years, officials and analysts say al-Sadr wants to keep Tehran at arm's length for political reasons amid the Iraqi public's strong nationalist feeling. Still, Iranian money and weapons continue to flow to al-Sadr because of their shared animosity against the U.S.
The third Shiite militia targeting Americans in Iraq is Asaib Ahl al-Haq, or Band of the People of Righteousness, a splinter Sadrist group that now competes with the Promised Day Brigade for support.
It does not have al-Sadr's backing, and an Iraqi close to the extremist group said it relies on Iran for support, including around $5 million in cash and weapons each month. Officials believe there are fewer than 1,000 Asaib Ahl al-Haq militiamen, and their leaders live in Iran.
The Iraqi intelligence official estimated about 3,000 Shiite militiamen _ two-thirds of them Mahdi Army _ were jailed by U.S. forces during the height of the war but later released by Iraq's government because of a lack of evidence to hold them. Most of them have made their way back to the front lines, the official said, more fueled by anger at American troops than ever.
Former Marine Ashwin Madia, who served in Iraq in 2005-06 and is interim chairman of VoteVets.org, a veterans advocacy group that has been critical of the Iraq war, said the deadly month should convince President Barack Obama to pull U.S. troops out by the end of the year as promised.
"If we stay in Iraq past our deadline, there is no reason to believe that violent attacks won't further increase, leading to more American deaths," Madia said Thursday.
Buchanan, the U.S. military spokesman, said the attacks are "not going to have an impact on us leaving or staying" because that decision will mostly be up to Iraq's government.
But he raised the specter of Iran using the militias to keep Iraq unstable so it can extert more influence once U.S. troops leave.
"Their overall preference is a weak Iraq," he said.
Associated Press Writers Rebecca Santana in Baghdad and Sameer N. Yacoub in Amman, Jordan, contributed to this report.