US officials have raised the possibility of a complete military withdrawal from Afghanistan for the first time, as President Hamid Karzai arrived in Washington for three days of discussions over military and economic ties.

In a briefing for journalists in advance of Karzai's visit, Ben Rhodes, deputy national security adviser, said the White House is prepared to consider all options for US troop levels after 2014, including a so-called "zero option" if conditions allowed.

On Friday Karzai holds his first face-to-face talks with President Barack Obama since last year's Nato summit in Chicago, shortly after the pair had signed a long-term strategic framework agreement.

The Obama administration is committed to withdrawing the majority of its 68,000-strong military stationed there by the end of next year –

with the size of the remaining force still to be decided, as well as the key question of legal immunity for US military operating in the country post-2014.

The talks between the two governments were "not aiming to keep a certain number of US troops in Afghanistan", said Doug Lute, deputy assistant to Obama and White House coordinator for South Asia. The final number would be "significantly lower" than the 68,000 troops currently on the ground, Lute said.

"They are going to be talking about missions and authorities, not numbers," Rhodes said.

Asked if the troop level options included zero, Rhodes replied: "That would be an option we would consider." Later he added: "We wouldn't rule out any option … we're not guided by keeping any [specific] number of troops in the country."

The White House warned that no agreements or decisions are expected to result from this week's visit by Karzai, describing it as "a good time for the two presidents to sit down and consult" ahead of the US military draw-down and the Afghan elections scheduled for April 2014.

Under the strategic framework agreement signed last year, some US troops may remain to train Afghan forces and continue to fight al-Qaida cells.

General John Allen, the Nato commander and top US general in Afghanistan, has recommended keeping between 6,000 and 15,000 troops in the country after 2014. An unnamed US official told Reuters the White House has asked for scenarios for between 3,000 and 9,000 troops to remain.

But the Afghan leader is said to want an end to US military operations in villages, as well as protection from militants based across the border with Pakistan.

The final number of any US forces in Afghanistan after 2014 would depend on the perceived strength of al-Qaida and its affiliates in the country, the progression of Afghan security forces, and the legal protection granted to US forces by the Afghan government – the last a sticking point in the bilateral security agreement being negotiated between the two governments with a deadline of November this year.

"I think they will have very candid discussions about the sorts of immunities that the bilateral security agreement might have," Lute said.

Karzai also wants the US to provide helicopters, heavy weapons and other advanced military equipment for Afghanistan's army as well as warplanes for the Afghan air force, and for humanitarian and reconstruction aid to be channelled through Afghan government ministries rather than via western aid agencies. Kabul has accused the US of fostering corruption by giving funding directly to warlords.

Officials are also to broach the on-again, off-again peace talks between the Taliban and the Afghan government.

The prospects for talks has been helped by Pakistan's recent release of groups of imprisoned Taliban commanders, including eight people on New Year's Eve, following an improvement in the Afghan-Pakistan relations that are crucial to any hopes of a peaceful settlement.

Hopes have been further raised by a meeting in France between the Taliban and the Afghan high peace council last month, which US officials have described as "promising". Direct talks with the Karzai government have been ruled out by the Taliban, which wants to negotiate with the American government, while the US says that the Taliban should speak directly to the Afghan government.

"We have a clearer path toward Afghan-led peace talks than we have had in the past, and I think that is what will be discussed," Lute said.

The Afghan leader will also meet secretary of state Hillary Clinton on Thursday – who is back at work after hospitalisation from a blood clot and concussion – as well as outgoing defense secretary Leon Panetta.

Karzai also plans to give a high-profile speech at Washington's Georgetown University.

Karzai is to visit his ally Asadullah Khalid, the head of Afghanistan's homeland security agency, who is in the US receiving medical treatment after being injured in a Taliban assassination attempt in Kabul last month.