General John Allen, Commander of the International Security Assistance Force (ISAF), speaks with U.S. Defense Secretary Leon Panetta, at a NATO meeting of Defense Ministers at NATO Headquarters in Brussels last month. (Jacquelyn Martin/AP)

The top U.S. commander in Afghanistan said Tuesday that, once a scheduled 23,000 U.S. troops are withdrawn by the end of September, he does not expect to consider additional drawdowns until next year.

“I’ll give the president my best military advice with regard to the combat power that we’ll need to accomplish this mission, probably in 2013,” Gen. John R. Allen told Congress. “I’m not sure that I’d be able to see out to ’14 at that point, but I’d probably have a pretty good feel for it.”

The United States and NATO have agreed to withdraw all combat troops by December 2014. By then, the U.S.-led coalition will have transferred security authority to Afghan forces throughout the country, Allen said. “But we will still have combat forces in Afghanistan all the way to the end.”

Allen’s comments appeared to place a military marker in the path of the rapid withdrawal advocated by some lawmakers and, according to opinion polls, by a majority of the American public.

The question, which the administration has barely begun to discuss, is how fast to withdraw the 68,000 troops who will remain after September. During a news conference last week, President Obama called for a “gradual pace” that “doesn’t result in a steep cliff at the end of 2014.”

Allen and other commanders have indicated that they would prefer that all 68,000 troops remain through most of 2013 for an additional summer of fighting. Administration critics, including the leading Republican presidential contenders, have accused Obama of undermining the war effort by signaling withdrawal plans at all, of following the political winds in heading for an early exit, and of not listening to the advice of military commanders.

Rep. Howard P. “Buck” McKeon (R-Calif.), chairman of the House Armed Services Committee, asked Allen whether he had the administration’s assurances that “you can have the forces you believe you need through the end of the 2013 fighting season.”

In what appeared to be a carefully worded reply, Allen managed to be both pointed and respectful of presidential authority. “I have been given assurances by the White House that we’re in a strategic conversation,” he said. “There has been no number mentioned. There has been no number that has been specifically implied.”

So far, he said, the conversation has been “excellent,” and he is confident that any decision “will account for my recommendation, the recommendation of the theater commander, and the Joint Staff in this process.”

When McKeon asked whether the White House “has always followed your best military judgment,” Allen replied, “As the commander in Afghanistan, it has, sir.”

Allen gave a generally upbeat assessment of the war, saying that the United States is “on track” to achieve its military goals. The capabilities of Afghan security forces, he said, are “better than we thought” as they move toward assuming full security control.

“To be sure, the last couple of months have been trying,” Allen said. “None of us harbor illusions. We know that we face long-term challenges as well.”

He acknowledged strains between coalition and Afghan forces, including “revelations that American troops had mishandled religious texts” and “what appears to be the murder of 16 innocent Afghan civilians at the hands of a U.S. service member.”

In addition to the military’s criminal investigation of Staff Sgt. Robert Bales, the suspect in the shooting deaths of the civilians, Allen said, there was an “administrative investigation of the entire command and control process,” conducted by the U.S. command in Afghanistan, looking into why and how Bales was assigned there.

But overall, Allen said, “I assure you, the relationship . . . remains strong.”

“Throughout history,” he said, “insurgencies have seldom been defeated by foreign forces. Instead, they have been ultimately beaten by indigenous forces.” Transition to Afghan forces, he said, “is the linchpin of our strategy, not merely the ‘way out.’ ”

Allen reiterated the importance of military night raids on Afghan homes in U.S. apprehension of Taliban commanders and said that development of village police in the Afghan countryside was continuing with the assistance of U.S. Special Operations forces there.

Last week, Afghan President Hamid Karzai demanded that U.S. forces be withdrawn from Afghan villages into centralized bases and that night raids be approved by judicial warrants, even when conducted in partnership with the Afghan army.

U.S. officials have said that they are negotiating the warrant issue with the Afghan government, and Denis McDonough, the Obama administration’s deputy national security adviser, noted Tuesday in an interview with National Public Radio that the United States, in special security courts, has a system of judicial warrants for such operations.

It is “reasonable to expect we would do the same kind of thing in Afghanistan,” McDonough said. Similar restrictions requiring judicial warrants were placed on U.S. troops in Iraq.

Allen did not directly address Karzai’s demand that U.S. troops withdraw from Afghan villages. Obama and Karzai, he said, were “in full agreement” that Afghan forces will be completely in the lead “on Dec. 31, 2014.”

Lawmakers showed little appetite for pressing Allen on larger issues of the war and growing public calls to end it. Several, including Rep. Walter B. Jones (R-N.C.), a longtime advocate of troop withdrawal, stated their positions that war funding should stop.

“If we get into 2014 and see President Obama or a Republican president, and Afghans are not trained where they need to be, and we’re spending money and losing lives, will you say to the next administration, ‘You need to stay on the timetable [for withdrawal]?’ ” Jones asked.

“I’ll be honest with you now, and I’ll be honest with the next administration,” Allen replied. “It’s my moral obligation to ensure that this force is resourced. . . . I believe this strategy will work. . . . If I think that’s coming off the rails, congressman, I will let you know that.”