WASHINGTON — President Barack Obama's chief spokesman said today that Obama will make a decision shortly about how many additional troops to send to Afghanistan, and when.

"Without getting into broad timelines, I don't think this is anything that involves weeks," White House press secretary Robert Gibbs said when asked about the timing of Obama's decision. The presidential spokesman underscored that Obama's move would come shortly.

Anticipation of the troop build-up in Afghanistan has been high since Defense Secretary Robert Gates said last Tuesday that Obama was days away from announcing his decision. Yet no formal announcement has emerged.

Gibbs spoke with reporters aboard Air Force One as Obama and his family flew back to the Washington area after a long weekend in his hometown of Chicago.

Obama has been widely believed likely to send fresh forces to the Afghan battle even as a wide review of U.S. strategy and goals there gets fully under way. Gates had told a Pentagon news conference last week that Obama "will have several options in front of him."

Gates suggested, as have other officials, that the ground commander in Afghanistan would eventually get all the forces he has asked for, but no more.