Surge in Deaths Reveals More Lethal Foe

"There are so many variables," Rubaie said Saturday. "What is the level of the insurgency, of terrorism? What is the position of regional countries" accused of harboring insurgents?

On Thursday, Alston, the military spokesman, cited the continuing buildup of Iraqi troops and what he described as successes against the insurgency. Asked for evidence, he said 13 vehicle bombings were recorded last week, three of them suicide attacks. He said both figures were the lowest since April.

"When I look at the bar charts, it's a clear indication to me that the tempo of suicide attacks has decreased," Alston said.

Military spokesmen said at the time that they would provide overall figures on vehicle, suicide and roadside bombings. The figures had not been released by late Saturday.

U.S. and Iraqi leaders say Iraqi-led raids in Baghdad and U.S.-led raids in the western province of Anbar -- the scene of the past week's heaviest losses -- have disrupted insurgents' command and supply lines and reduced the number of bombings.

The capture or killings of numerous lieutenants of the insurgent leader Abu Musab Zarqawi and others also are believed to have thwarted specific attacks, commanders say. Insurgent groups have been forced to reorganize to make up for the leadership losses, with many moving under the umbrella of al Qaeda in Iraq, Zarqawi's group, according to some Western intelligence officials and insurgents.

But the U.S. military says its enemy is adaptive: Perhaps because crackdowns have disrupted supply lines for bombs, small arms appear to be used more. When U.S. forces sweep regions like Anbar, troops and residents say, insurgents return as soon as the Americans leave.

Additionally, the U.S. military presence here has helped attract radical young Muslim men from inside and outside Iraq. American military officials last year put the number of insurgents as low as 3,000; official estimates last month ranged from 16,000 to 20,000, including perhaps 1,000 foreign fighters.

Iraqis and Americans blame the foreign fighters for introducing suicide bombings to Iraq, terrorizing daily life in Baghdad and other cities and solidifying most public opinion against the foreign extremists.

But bombings have also achieved insurgents' aim of reducing support for Jafari's interim government. Public criticism of Jafari's government as ineffective grows when the insurgents often-cyclical bombing campaigns are on the upswing.

As the political process evolves, shifting power to Iraq's Shiite Muslim majority, the Sunni Arabs who make up the bulk of the insurgency have focused with increasing frequency on attacking Shiites and political figures -- a shift that insurgent leaders say came from the top down, starting with Zarqawi.

"We fight the Americans and the Shiites," said a 55-year-old Iraqi insurgent leader in Ramadi who calls himself Abu Hasan Ansari. "But because the Shiite danger to Islam became bigger than the American danger, the priority is to fight the Shiites before the Americans."

Staff writer Josh White in Washington contributed to this report.