The war council with Vice President Joe Biden, Secretary of State Hillary Clinton, Defense Secretary Robert Gates and other officials got under way at 8:13 p.m. (0113 GMT on Tuesday) in the White House Situation Room.
It is the ninth such meeting as Obama nears a decision on whether to add as many as 40,000 troops to an eight-year-old war that began after the September 11 attacks and that has begun to try the patience of Americans.
US officials and Western diplomats said they expected Obama's announcement next week, before a NATO meeting on December 7 in Europe in which alliance members could agree to send thousands of additional trainers.
The White House has given no firm date for the news, but "the first possible time would be sometime next week," presidential spokesman Robert Gibbs said.
There are about 110,000 foreign troops, including 68,000 US soldiers, in Afghanistan fighting Taliban insurgents.