US President Barack Obama said Wednesday that there is no "immediate decision pending" on sending more troops to Afghanistan.

"I just want to be absolutely clear on this because there has been a lot of discussion in the press about this ... there is no immediate decision pending on resources," said the president after meeting with Canadian Prime Minister Stephen Harper at the White House.

"You don't make determinations about resources, and certainly you don't make determinations about sending young men and women into battle, without having absolute clarity about what the strategy's going to be," said the president.

"I think that what is clear is that we have lacked as clear of a strategy and a mission as is necessary in order to meet our overriding objectives," added Obama, who had vowed to send additional 21,000 troops to the country, bringing the force to about 65,000 by the end of this year.

However, Stanley McChrystal, top US commander in Afghanistan, on Tuesday submitted an assessment report on situation in Afghanistan, claiming that the military is likely to request more troops deployed to defeat Taliban's resurgence.

Obama also said he was "extremely grateful" to the Canadian forces for their suffering losses in Afghanistan.

Canada, following Britain and Germany with some 2,800 troops stationed in Afghanistan, has offered important assistance, including more than 820 million US dollars, for Washington since the war targeted al-Qaida and Taliban began in October 2001.