President Barack Obama will speak Tuesday night on his new Afghanistan strategy. (Jim Young/Reuters)U.S. President Barack Obama ordered military officials to begin carrying out his new strategy in Afghanistan, two days before his speech to unveil a plan that includes the deployment of thousands of more troops.

White House spokesman Robert Gibbs said the rollout began Sunday after Obama spoke with senior officials, including Secretary of State Hillary Rodham Clinton, Secretary of Defence Robert Gates, National Security Adviser James Jones, Gen. Stanley McChrystal and Karl Eikenberry, ambassador to Afghanistan.

Gibbs said it was at that time that the order for the military to go ahead with new deployments became official.

As well, Gibbs said, Obama began briefing world leaders, including French President Nicolas Sarkozy, and would be in touch later with British Prime Minister Gordon Brown and Russian President Dmitry Medvedev.

On Tuesday night at the United States Military Academy in West Point, N.Y., Obama is expected to announce he will be sending more than 30,000 troops to Afghanistan.

Brown has said that several allied nations will offer a total of 5,000 more troops, which, combined with Obama’s troops, would be close to the 40,000 more soldiers McChrystal has called for.

The escalation, which would take place over the next year, would put more than 100,000 American troops in Afghanistan at an annual cost of about $75 billion US.

Obama's speech will include a revamped approach to train Afghan security forces to eventually take over from the U.S. It will also talk about an exit strategy, stressing that he doesn't plan an open-ended U.S. commitment.

But Obama could face roadblocks in the House and Senate, particularly by members of his own party who are wary of an increased troop commitment and the costs associated.

Democratic Senator Carl Levin, chairman of the Senate armed services committee, said greater numbers of Afghan army and police are central to succeeding in the war.

Levin said it's not clear what role the tens of thousands of additional U.S. combat troops would play in that buildup and that Obama has to make a compelling case for it on Tuesday.

"The key here is an Afghan surge, not an American surge," Levin said. "We cannot, by ourselves, win [the] war."

With files from The Associated Press