MEXICO CITY — U.S. Secretary of Defense Robert Gates on Tuesday acknowledged that a seven-month lull in U.S. troops deaths in Iraq has come to an end and blamed the bloodshed on Shiite Muslim militiamen who have bombarded the Green Zone and key parts of Baghdad with rockets and mortar rounds.
April has been the bloodiest month for Americans in Iraq since September, with 44 troops killed, compared to 39 in March and 29 in February.
April also was the first month since November that saw U.S. Marines killed in once restive Anbar province. Two Marines were killed in April in Anbar, which had been the deadliest part of Iraq for U.S. troops before a widely heralded tribal rebellion drove Sunni militants from the province.
That the number U.S. troop deaths is rising even as the U.S. has begun withdrawing troops that had been sent to Iraq as part of the so-called surge has some officials fretting that the U.S. and Iraqi forces cannot sustain what had been billed as security gains without the additional forces. So far three of the five surge brigades have left.
Deaths also rose as the surge troops were moved into place last year. But they quickly fell to their lowest levels in more than two years once the roughly additional 30,000 troops were in place, bringing total U.S. forces in Iraq to 170,000.
Some now fear that as more U.S. troops go home, violence will increase.
During an evening roundtable discussion with reporters here, Gates blamed the current rise in violence on Shiite cleric Muqtada al Sadr, saying that while the leader of the Mahdi Army has not lifted a ceasefire he imposed a year ago, he has made comments that may have encouraged his followers to target American troops.
"It has more to do with a mixed message, I think, coming out of Sadr in terms of whether or not his followers should maintain the ceasefire or are they at liberty to go after U.S. troops," Gates said.
Gates also noted that U.S. forces had entered Baghdad's Sadr City, a Mahdi Army stronghold, this month in an effort to quell violence that erupted between Sadr supporters and Iraqi security forces after Iraqi Prime Minister Nouri al Maliki launched an offensive against the Mahdi Army in the southern port city of Basra.
Since then, fighting has been brutal. On Tuesday, militiamen fired rocket propelled grenades during an attack on a U.S. patrol. The U.S. retaliated with a 200-pound guided rocket that U.S. officials said killed 28 militiamen. Local authorities said civilians were among the dead.
Still, Gates said the drawdown will continue and will be finished by the end of July, leaving 15 combat brigades or roughly 140,000 troops in Iraq. That is 8,000 more than before the surge began.
Gates also confirmed that a second U.S. aircraft carrier had arrived in the Persian Gulf, but denied that the presence of two aircraft carriers in the region was a precursor to military action against Iran. Gates would not discuss details of the deployment; other reports said the two carriers might overlap in the area for only a few days.
"I don't think we'll have two carriers there for a protracted period of time, so I don't see it as an escalation," he said. "I think it could be seen, though, as a reminder."
The secretary is visiting Mexico in part to reassure leaders here that the U.S. remains committed to regional issues despite the war. He called on Congress to pass a $500 million anti-drug trafficking assistance package called the Merida Initiative. The program would provide Mexico's army with equipment and training.