Washington - US President Barack Obama has signed off on sending at least 10,000 more troops to Afghanistan and an announcement on the deployment could come later Tuesday, US television reported.

This would be the first deployment of a larger buildup expected to take place in Afghanistan this year to counter a resurgent Taliban and al-Qaeda that has brought about some of the worst violence in years.

There are about 34,000 US solders already in Afghanistan, but the commander there, General David McKiernan, has requested an increase of 30,000 troops. Obama has said he wants to begin pulling forces from Iraq to refocus the effort on Afghanistan.

In an interview with Canadian Broadcasting Corporation Tuesday ahead of his first trip abroad to Ottawa, Obama said he is conducting a review of the situation in Afghanistan and would "very soon" detail his initial plans.

"I am absolutely convinced that you cannot solve the problem of Afghanistan, the Taliban, the spread of extremism in that region solely through military means," Obama said. "We're going to have to use diplomacy, we're going to have to use development."

Obama acknowledged that the conflict in Afghanistan "appears to be deteriorating at this point" but argued it is still winnable.

Obama is scheduled to arrive in Ottawa for a short visit and meeting with Canadian Prime Minister Stephen Harper. Canada plans to pull all of its combat troops out of southern Afghanistan by 2011. The Obama administration has been hopeful that allies would be willing to commit more troops.

Obama told CBC he does not intend to arrive in Canada with specific requests.

"What I will be communicating is the approach that we intend to take," he said. "Obviously I'm going to be continuing to ask other countries to help think through how do we approach this very difficult problem. But I don't have a specific "ask" in my pocket that I intend to bring out in our meetings." (dpa)