He said that he would outline his Afghanistan strategy after Thanksgiving, adding, “I feel very confident that when the American people hear a clear rationale for what we’re doing there and how we intend to achieve our goals, that they will be supportive.”

Though he and his advisers have drawn up benchmarks to measure progress and put pressure on the Afghan government to do its part, Mr. Obama offered no details in his public remarks on Tuesday. He was also silent on precisely what would constitute finishing the job in Afghanistan or how soon he envisioned being able to begin extricating the United States from the war there.

While the troop levels he orders will go a long way toward defining his position, the White House has stressed that Mr. Obama’s review has gone far beyond the numbers to better define the military and civilian-aid components of the effort in Afghanistan, how they fit into efforts to combat Al Qaeda in Pakistan and how to ensure that the American commitment in the region is not open-ended.

At the meeting on Monday night, Mr. Obama went around the table in the White House Situation Room asking his senior advisers for summations of their individual assessments and to voice any concerns they still had, said an administration official who was briefed on the two-hour meeting.

“There was a lot of back and forth,” said the official, with Mr. Obama interjecting questions and top aides cutting each other off at times. When the meeting finished shortly after 10 p.m., some of the senior advisers lingered in small groups to continue their discussions, said the official, who like others interviewed for this article spoke on the condition of anonymity because of the meeting’s confidentiality.