"You'd find the enemy regaining ground, re-establishing sanctuary, building more" roadside bombs, Maj. Gen. Rick Lynch told a Defense Department news conference. "The violence would escalate. It'd be a mess."
Lynch was responding to a question on the possible effects if officials were to decide not to extend beyond the summer the troop buildup President Bush ordered early this year.
Mr. Bush sent an additional 30,000 troops to try to pacify Baghdad and wants Congress to wait until September for an assessment on how it is working. But an increasing number of U.S. lawmakers are already convinced the policy is failing and should be changed.
Lynch said he did not know how long the extra forces would be needed.
"Those surge forces are giving us the capability we have now to take the fight to the enemy," Lynch said by video conference from Iraq. "If those surge forces go away, that capability goes away."
"Over time, we can turn the area over to Iraqi security forces, and then we'll be ready to do something that looks like a withdrawal," Lynch said. "But that's not going to happen any time soon."
In the latest setback to the increasingly unpopular war strategy, Republican stalwart Sen. Pete Domenici said Thursday that he already has decided he wants to see an end to combat operations and U.S. troops heading home from Iraq early in 2008.
Domenici, who has served 35 years in the Senate, is the latest of several party loyalists and former war supporters to abandon Mr. Bush on Iraq in the past 10 days. They have urged a change sooner rather than later and further isolated the Republican president in his attempt to defend the unpopular war.
Last week, Sens. Richard Lugar and George Voinovich said the U.S. should significantly reduce its military presence in Iraq while bolstering diplomatic efforts. Sen. John Warner, a senior Republican military expert, is expected to propose a new approach this month.
, Lugar said the U.S. should reduce the military's role in Iraq and called on Mr. Bush to press other diplomatic and economic initiatives instead. Because of Lugar's position as the top Republican on the Foreign Relations Committee, his speech was a considered a blow to the administration as it tries to shore up sagging political support for the unpopular war.
"I do not support an immediate withdrawal from Iraq or a reduction in funding for our troops," Domenici said. "But I do support a new strategy that will move our troops out of combat operations and on the path to coming home."
With Congress on its holiday break, Domenici made his views known at a news conference in Albuquerque, N.M., though he said he has not talked to the administration about wanting a strategy shift.
"I have carefully studied the Iraq situation and believe we cannot continue asking our troops to sacrifice indefinitely while the Iraqi government is not making measurable progress to move its country forward," he said.
The senator said the situation in Iraq is getting worse. He said he now supports a bipartisan bill that embraces the findings of the independent Iraq Study Group.
In December, the group said the primary mission of U.S. troops should evolve to supporting Iraqi security forces. The report also said the U.S. should reduce political, military or economic support for Iraq if the Baghdad government cannot make substantial progress.
The group said combat troops could be out by March 2008 if specific steps were taken.