U.S. President Barack Obama will announce Tuesday that troops will start leaving Afghanistan in July 2011, according to senior administration officials. (Pablo Martinez Monsivais/Associated Press)

U.S. President Obama will ask NATO allies to contribute up to10,000 new troops to the International Security Assistance Force in Afghanistan when he delivers a prime-time speech Tuesday night, according to diplomats.

A European official told The Associated Press that the troop number — between 5,000 and 10,000 — was included in an official NATO document Washington sent out ahead of Obama's speech from West Point, N.Y.

NATO's force in Afghanistan now stands at about 40,000 troops.

Canada, a NATO country, is not likely to contribute troops. Prime Minister Stephen Harper has repeatedly said that he will adhere to a motion passed in Parliament and not extend Canada's military mission beyond 2011.

Obama, who will use the TV speech to unveil his new strategy for Afghanistan, is expected to announce the United States will send 30,000 additional troops to Afghanistan on an accelerated timetable.

He will also declare that troops will start being withdrawn in July 2011, White House officials confirmed.

While Obama intends for troops to begin leaving Afghanistan in 19 months, one official said the president will not offer a clear date for the end of the war.

The primary mission of the additional forces will be to target the Taliban-led insurgency and protect the Afghan population, as well as improve the training and mentoring of Afghan security forces, the officials said.

The additional troops will arrive as early as Christmas, and it's expected all forces will be in place by summer.

The escalation over the next year will put U.S. troop strength in Afghanistan at 100,000, at an annual cost of about $75 billion US.

Canada's military mission to Afghanistan began soon after the attacks on the United States on Sept. 11, 2001. The current mission in Kandahar, which began at the end of 2006, includes 2,800 troops focused around an infantry battle group.

Since 2002, 133 Canadian soldiers have been killed serving in the Afghanistan mission, resulting in the highest per-capita death rate among foreign armies in Afghanistan. One diplomat and two aid workers have also been killed.

Mixed reactions

Obama's new Afghanistan plan is generating mixed reactions from both politicians and citizens.

Despite the president's earlier order to deploy 21,000 troops, the war in Afghanistan has worsened. Less than half of Americans support another troop increase, suggested a Gallup poll of more than 1,000 people in November.

Outside the White House on Tuesday, a small band of anti-war demonstrators protested the possibility of a troop surge.

Members of Obama's own party are at odds with the president over his costly strategy. Powerful Democrats, including Carl Levin and Congressman John Larson, are pushing Obama for a war tax to pay for the additional troops.

Meanwhile, Obama has found some support from Republicans, including South Carolina Senator Lindsey Graham.

"From my point of view, the president is correct in assessing that Afghanistan is a war that must be won," Graham said.