BAGHDAD — The four U.S. soldiers who died in a series of roadside bombings Wednesday lifted the number of American service members killed in April to a seven-month high of 50.
Civilian deaths reported by the Iraqi government also reached the highest levels in months as Baghdad experienced intense clashes triggered by an Iraqi government crackdown against Shiite Muslim militias.
U.S. commanders say Sunni Arab militants are also attempting to reassert themselves by staging suicide bombings and other high-profile attacks in parts of the country where they have come under pressure since last year.
The jump in deaths raises questions about whether U.S. and Iraqi forces can consolidate last year's security gains as most of the additional 28,500 American troops deployed to the country return home.
"We have said all along this will be a tough fight," said Army Maj. Gen. Kevin Bergner, a U.S. military spokesman. "There will be periods where we see the extremists, these criminal groups and Al Qaeda terrorists, seek to reassert themselves and reignite violence for their own purposes."
U.S. commanders will be relying increasingly on their Iraqi counterparts to provide security as the American presence diminishes from a peak last year of nearly 170,000 to about 140,000 by July.
Navy Rear Adm. Patrick Driscoll, another military spokesman, said the Iraqis added more than 105,000 to their forces in the time the U.S. brought in five additional combat brigades.
"So we've seen a substantial surge within a surge, and they're continuing to grow," Driscoll said.
U.S. commanders say the Iraqi military and police are becoming more capable. Though they acknowledge that the government crackdown was poorly planned at the start, they say the Iraqi military quickly mobilized reinforcements and regained control of the southern oil hub of Basra with the help of U.S. and British air power.
But the government did not appear to have anticipated the fierce backlash from militiamen loyal to radical Shiite cleric Muqtada Sadr in Baghdad, where clashes continue daily.
Many of the militiamen's attacks are directed against U.S. forces, who have moved into the southern portion of the cleric's stronghold in the capital, the slum known as Sadr City, in a bid to stop rockets and mortar rounds from being fired toward the troops' bases and the city's fortified Green Zone.
