President Barack Obama addresses the nation Wednesday to announce his plan for drawing down U.S. forces in Afghanistan, nearly a decade after the war began.

Defense officials have been quoted as saying that Mr. Obama will call for an initial withdrawal of about 10 percent of the U.S. forces in Afghanistan — with 5,000 troops to leave first, followed by another 5,000 before the year's end.

White House spokesman Jay Carney says the president will explain how he will implement the strategy he outlined for Afghanistan in December 2009, when he approved a surge of 30,000 troops and promised the first American forces would leave in 18 months.

U.S. officials say the remainder of the surge, some 20,000 American troops, may leave Afghanistan by the end of 2012.

Carney called early reports of the size and speed of the withdrawal “speculation.”

In his speech Wednesday night at the White House, President Obama is also expected to reaffirm the U.S. and NATO commitment to transfer security responsibilities to Afghan forces by 2014. The United States currently has about 100,000 troops in Afghanistan, and media reports estimate the U.S. government is spending $10 billion each month fighting the war.

U.S. opinion surveys indicate that Americans are increasingly weary and disillusioned about the war. A Pew Research poll released Tuesday shows a record 56 percent of Americans say U.S. troops should be brought home as soon as possible.

Defense Secretary Robert Gates said Tuesday the president has to take into account sustainability at home, both in Congress and among the American public, as well as conditions on the ground in Afghanistan.

Gates acknowledged the concerns over Afghanistan, saying the American people are “tired of a decade of war.” He noted there are “a lot of reservations” in Congress about the war and the level of U.S. commitment.

Hours before Mr. Obama's speech Wednesday, lawmakers in Congress passionately debated the costs and benefits of the war.

White House spokesman Carney said the president has remained focused on achieving his objectives in Afghanistan — disrupting, dismantling and defeating al-Qaida, reversing Taliban momentum, and preventing Afghanistan from becoming a safe haven for terrorists.