By JAMES ROSEN
WASHINGTON - Under tough questioning by senators from both parties Thursday, top military generals gave a sobering portrait of the Iraq war, their testimony punctuated by a new eruption of violence that killed 40 people in a city near Baghdad.
In a series of testy exchanges, the senators and the generals sparred over the competence of Iraqi soldiers, the timing of a possible U.S. troop withdrawal, potential outcomes of next month's constitutional referendum and faltering control of towns in the Sunni triangle of insurgent activity.
During an intense grilling by Republican Sen. John McCain of Arizona, Gen. George Casey, commander of U.S. and allied forces in Iraq, acknowledged that only one battalion of Iraqi soldiers is fully prepared to operate without help from U.S. troops - far fewer than previously claimed by the Pentagon.
"The previous report, you had three battalions," McCain said. "Now we're down to one battalion."
Casey responded: "Right. And things changed in the battalions. I mean, we're making assessments on personnel, on leadership, on training. There are a lot of variables that are involved here, senator."
The general's concession contradicted recent statements by President Bush, who said last week and again Wednesday that a growing number of capable Iraqi forces are maintaining control of more and more towns after insurgents are ousted from them.
The new assessment troubled Sen. Susan Collins, a Maine Republican.
"That contributes to a loss of public confidence in how the war is going," she said. "It doesn't feel like progress when we hear today that there is only one Iraqi battalion fully capable."
Three-quarters of the U.S.-trained Iraqi army is capable of engaging in combat with support from American forces, Casey said. He said more than 30 battalions can take the lead in an offensive, but only one - consisting of 300 to 1,000 soldiers - can operate entirely on its own.
In Iraq, three suicide car bombs exploded Thursday within minutes of one another at a bank, a vegetable stand and another location in downtown Balad, 50 miles north of Baghdad. The blasts killed 40 people and wounded or burned scores more, according to a hospital official.
In a separate attack, U.S. military officials said five Marines died Wednesday in a roadside bombing during combat in the western town of Ramadi, bringing to 13 the number of American soldiers slain in Iraq this week.
The Bush administration took another hit on Iraq from a federal judge. Alvin K. Hellerstein, a district judge in New York, ordered the government to release dozens more photos of inmates being abused at the Abu Ghraib prison.
McCain, a former Vietnam prisoner of war, and Sen. Carl Levin, a Michigan Democrat, led the interrogation of Casey and other military leaders at a hearing of the Senate Armed Services Committee.
Defense Secretary Donald Rumsfeld, Gen. Richard Myers, chairman of the Joint Chiefs of Staff, and Gen. John Abizaid, head of U.S. Central Command, also testified at the hearing, but Casey bore the brunt of the senators' frustration.
McCain, who challenged President Bush for the Republican presidential nomination in 2000 but campaigned for his re-election last year, grew exasperated as he asked why insurgents keep regaining control of towns after U.S.-led offensives.
"How many times, General Casey, are we going to read about another offensive in Fallujah, Mosul, Ramadi, Al-Qaim - where we go in, we take control and we leave, and the bad guys come in?" McCain asked. "How often are we going to read that, General Casey?"
Casey responded: "Hopefully, not too frequently, senator. . . . The issue has always been the availability of Iraqi security forces to remain and retain control."
Levin repeatedly pressed Casey about a partial withdrawal of U.S. troops. The general at first said, "We certainly do look to do that over the course of next year." But when Levin asked him whether the withdrawal could begin in the spring, Casey said, "Senator, the next 75 days are going to be critical in what happens after that."
Casey referred to two key political events: a referendum on a draft constitution Oct. 15 and elections for a permanent government scheduled for mid-December.
"You're taking a very big gamble here," McCain told Casey. "I hope you're correct. I don't see the indicators yet that we are ready to plan or begin troop withdrawals, given the overall security situation."
Casey acknowledged that the political environment could deteriorate further if a majority of Sunni Muslims vote against the constitution next month. The minority sect controlled Iraq under Saddam Hussein, a Sunni who was toppled after the March 2003 U.S. invasion, but Shiites and Kurds have asserted power as the country tries to move toward democratic rule.
"As we've look at this, we've looked for the constitution to be a national compact, and the perception now is that it's not, particularly among the Sunni," Casey said.
Rumsfeld added, "Current indication . . . is that a majority of the Sunnis will vote against it."
There are 149,000 U.S. soldiers in Iraq, with the number increasing in recent weeks in advance of the elections.
Bush warned Americans this week to expect fresh insurgent attacks in the coming weeks, similar to the violent surges that preceded earlier political milestones.