United States President Joe Biden meets Afghan President Ashraf Ghani and his former political foe, Abdullah Abdullah, on Friday to discuss Washington's support for Afghanistan as the last US troops pack up after 20 years of war and government forces struggle to repel Taliban advances.

The Oval Office meeting may be as valuable to Ghani for its symbolism as for any new US help because it will be seen as affirming Biden's support for the beleaguered Afghan leader as he confronts Taliban gains, bombings and assassinations, a surge in COVID-19 cases and political infighting in Kabul.

"At a time when morale is incredibly shaky and things are going downhill, anything one can do to help shore up morale and shore up the government is worth doing," said Ronald Neumann, a former US ambassador to Kabul. "Inviting Ghani here is a pretty strong sign that we are backing him."

Biden's embrace, however, comes only months after US officials were pressuring Ghani to step aside for a transitional government under a draft political accord that they floated in a failed gambit to break a stalemate in peace talks.

Biden's first meeting as president with Ghani and Abdullah, chairman of the High Council for National Reconciliation, will focus on "our ongoing commitment to the Afghan people" and security forces, said White House deputy press secretary Karine Jean-Pierre.

Biden has asked Congress to approve USD 3.3 billion in security assistance for Afghanistan next year and is sending 3 million doses of vaccines there to help it battle COVID-19.

Biden will urge Ghani and Abdullah, foes in Afghanistan's two last presidential elections, "to be a united front" and he will reaffirm US support for a negotiated peace deal, Jean-Pierre said.

US officials, however, have been clear that Biden will not halt the US pullout – likely to be completed by late July or early August – and he is unlikely to approve any US military support to Kabul to halt the Taliban's advances beyond advice, intelligence, and aircraft maintenance.

Ghani and Abdullah spent Thursday discussing the situation in Afghanistan with lawmakers on Capitol Hill.

The visit comes with the peace process stalled and violence raging as Afghan security forces fight to stem a Taliban spring offensive that threatens several provincial capitals and has triggered mobilizations of ethnic militias to reinforce government troops.

The crisis has fueled grave concerns that the Taliban could regain power - two decades after the US-led invasion ended their harsh version of Islamist rule – allowing a resurgence of al Qaeda. US and UN officials say the extremists maintain close links with the Taliban.

"The Pentagon and the intelligence community are saying it is very likely that al Qaeda will come roaring back. It is very likely that our soldiers and our troops may have to go back into Afghanistan," said US Representative Mike Waltz, a former Army officer who commanded US Special Forces in Afghanistan.

US officials respond that the United States will be able to detect and thwart any new threats by al Qaeda or other Islamists. The Taliban insist al Qaeda is no longer in Afghanistan.

US government sources familiar with US intelligence reporting describe the situation as dire. Ghani, they said, has been urged to do more to step up pressure on the insurgents while US-led coalition forces are still there.

Biden, who pledged to end America's "forever wars," announced in April that all US forces would be out of Afghanistan by the anniversary of the September 11, 2001, attacks by al Qaeda on the United States.

He made the decision even though a 2020 US-Taliban deal forged under former President Donald Trump set May 1 as the US pullout deadline.