WASHINGTON - Gen. David H. Petraeus on Tuesday left open the possibility of recommending that President Obama delay his plans to start withdrawing troops from Afghanistan next summer, if the new commander can't turn around the stalemated war.

"There will be an assessment at the end of this year, after which undoubtedly we'll make certain tweaks, refinements, perhaps some significant changes," Petraeus told a Senate panel of the battle plan and the timeline Obama has laid out.

"I want to assure the mothers and fathers of those fighting in Afghanistan that I see it as a moral imperative to bring all assets to bear to protect our men and women in uniform," he said. "Those on the ground must have all the support they need when they are in a tough situation."

The Senate Armed Services Committee quickly approved Petraeus for the job of running the Afghan war, and the full Senate was expected to confirm him Wednesday. The general is expected in Kabul by Friday.

Obama nominated Petraeus to take over from the disgraced Gen. Stanley McChrystal, fired last week for disparaging remarks about his civilian bosses. White House officials said Tuesday they were working to allow McChrystal to retire at the rank of four stars, with accompanying benefits.

Petraeus told senators Tuesday that he may change the war's battlefield rules, designed to limit civilian casualties and improve support for the foreign forces fighting the Taliban-led insurgency. Some troops and congressional Republicans complain they handicap U.S. forces.

Obama has said that troops would begin to leave in July 2011 but that the pace and size of the withdrawal will depend upon conditions.

Petraeus did not rule out a significant exodus then, as Vice President Biden favors, but he would not promise one either. Petraeus has previously said that he would recommend putting off any large-scale withdrawal if security conditions in Afghanistan cannot sustain it.

The general, credited with turning around the Iraq war after the height of sectarian violence there in 2006, told the Senate panel that Obama wanted him to provide unvarnished military advice.

He did not paint a rosy picture.

"My sense is that the tough fighting will continue; indeed, it may get more intense in the next few months," Petraeus said. "As we take away the enemy's safe havens and reduce the enemy's freedom of action, the insurgents will fight back."

Beneath bipartisan rounds of praise for Petraeus lay fault lines over the nearly nine-year war. A make-or-break military push across southern Afghanistan is stuck in neutral, though U.S. officials insist there are signs of progress and reason for hope.

"On the Democratic side, there is solid support" for the war, committee chairman Carl Levin (D., Mich.) said ahead of Tuesday's session. "But there's also the beginnings of fraying of that support."

As the number of troop deaths rise, support for the war is dropping in the United States and Europe. June is the deadliest month of the war so far, with the total U.S. deaths above 1,000, and the new British government says it wants its troops out in five years.

A careful student of politics, Petraeus gave something to everyone while leaving himself room to maneuver.

For Democrats and his White House masters, Petraeus endorsed Obama's revamped war strategy and the plan to begin withdrawing U.S. forces from the unpopular fight next July.

The exit plan isn't just a sop to American liberals opposed to the conflict, Petraeus said under questioning from skeptical Republicans.

He made clear he was wary of deadlines but said he valued the sense of urgency Obama's timeline conveys. "I'm convinced it was not just for domestic political purposes," he said. "It was for audiences in Kabul, who, again, needed to be reminded that we won't be there forever."

For Republicans uneasy about the strict rules of engagement, Petraeus promised a hard examination. In particular, he will look at the way the "tactical directive" is applied.

The directive is the guidance given to commanders on when they can rely on heavy firepower such as attack helicopters to protect troops under attack. McChrystal had limited the circumstances under which such bombing could be used.

Petraeus said he believed the rules and the reasoning behind them were basically sound. "That's an area we have to look very closely at because, of course, if you drop a bomb on a house, if you're not sure who's in it, you can kill a lot of innocent civilians in a hurry," he told the Senate panel.

At the same time, Petraeus said he was concerned that some commanders were "making this more bureaucratic or more restrictive than necessary when our troops and our Afghan partners are in a tough spot.

"And when they are in a tough spot, it's a moral imperative that we use everything we have to ensure that they get out of it," he said.

The only fireworks came when Sen. Lindsey Graham (R., S.C.) sharply questioned Petraeus about whether he agreed with White House suggestions that the pullout would occur on schedule, no matter what Afghanistan looks like in a year's time.

"Somebody needs to get it straight without doubt what the hell we're going to do in Afghanistan," Graham said.

Petraeus suggested that the infighting between U.S. military and civilian officials responsible for Afghanistan policy would end.

Several times throughout the hearing, Petraeus said he already had been in close contact with Karl Eikenberry, the top diplomat in Afghanistan who sparred with McChrystal. He said he also had spoken three times already with Afghan President Hamid Karzai and held a conference call with U.S. special representative Richard Holbrooke.

Petraeus said he and Eikenberry planned to meet in Brussels, Belgium, this week to confer with NATO officials before flying together to Kabul.

Afghan Aide for U.N. Is Slain

An Afghan man working for the United Nations was shot and killed in his vehicle Tuesday near a traffic circle in Kabul, the United Nations said.

The employee was driving

a pickup truck with the blue U.N. logo painted on the side. Another Afghan member of the United Nations inside the truck was not injured.

The shooting occurred

near Massoud Circle, an intersection near the U.S. Embassy and a U.S. military base. "The circumstances of the shooting are not yet clear," a U.N. statement said.

Elsewhere, U.S. and Afghan forces battled hundreds

of extremists from an al-Qaeda-linked group for a third day in Kunar province of eastern Afghanistan, the U.S. military said. Two U.S. soldiers were killed Sunday in the first day of the operation.

The attack was directed against insurgents believed responsible for a roadside bomb that killed five U.S. service members June 7.

The extremists were believed to be members

of the Haqqani group, a faction of the Taliban based in Pakistan that has ties to al-Qaeda.

- Associated Press