President Barack Obama would consider a plan for post-2014 Afghanistan that left no American troops in the country, a senior US official said Tuesday, as President Hamid Karzai headed to Washington.

Officials however stressed that Obama, mulling how fast to draw down US soldiers from the country, would not be guided by specific future troop levels, but would decide the fate of the American presence based on strategic needs.

Asked whether Obama would consider a scenario in which all US troops left and there was no residual force in Afghanistan, Ben Rhodes, a deputy national security advisor said: "That would be an option we would consider."

"We wouldn't rule out any option. We are not guided by the goal of a certain number of troops in the country. We are guided by the objective that the president has set," Rhodes told reporters.

Obama's goals are to ensure that Afghanistan's new national army has the capacity and equipment to defend itself and to ensure that Al-Qaeda cannot make a post-war comeback and again find safe haven.

Ahead of Karzai's visit, various reports citing US defense sources have put forward a range of possible plans, including the "zero option" for the residual level of the American commitment to Afghanistan.

The Wall Street Journal reported late last week that the Pentagon had prepared plans for a smaller presence in Afghanistan at the insistence of the White House.

The newspaper said the plans now prepared by the Pentagon call for leaving roughly 3,000, 6,000 or 9,000 US troops in the country.

The presence of US troops in Afghanistan after 2014 will also have to be governed by a status of forces agreement, which Obama and Karzai are expected to discuss at their talks at the White House on Friday.

US and international forces anticipate ending combat missions in Afghanistan this year, before moving to a training role with local forces until the end of 2014.