WASHINGTON - The White House on Tuesday said President Barack Obama has made a decision on Afghanistan drawdown, but was tight-lipped about other details, while media reports are indicating Obama will "likely" announce the drawdown of 10,000 troops.

"The parameters of the decision involve the beginning of the withdrawal of US forces," said Jay Carney, the White House press secretary, during Tuesday's regular briefing session.

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Obama "made the commitment that forces would begin to draw down in July 2011, and he is keeping that commitment, and that's what he will announce tomorrow evening," Carney added.

The press secretary said Obama's decision is within the framework of transition of security responsibilities to Afghan forces that is scheduled to complete in 2014, but the upcoming announcement will focus on the beginning of the drawdown.

Earlier in the day, Carney put out a statement saying Obama will address the nation from the White House at 8 pm Wednesday, to "lay out his plan for implementing his strategy - first unveiled in December 2009 - to draw down American troops from Afghanistan."

Carney said Obama's decision is not driven by the killing of al-Qaida mastermind Osama bin Laden, and while he is mindful of the limited resources the country has, the decision is not based on the monetary cost of war, but about the mission itself.

Obama made what "he believes is the right decision to be made as commander in chief," said Carney.

US media outlets have been speculating since Tuesday morning how many troops will exactly be pulled out. Reports later in the day have been indicating Obama is "likely" to announce the drawdown of 10,000 troops by the end of the year, with a possible 20,000 more out next year.