President Donald Trump's decision at his administration's sunset to pull back US troops from Afghanistan and Iraq is among his final attempts to keep his original campaign promise, but creates a policy vacuum and complicates the transition to Democrat Joe Biden in January.

Acting Defence Secretary Christopher Miller's announcement that the US troop strengths in those two countries would be reduced to 2,500 each by January 15 – just five days before Biden takes over – creates a policy vacuum there.

Miller said on Wednesday, “In the coming year, we will finish this generational war and bring our men and women home.”

Winding down of 2001 war

The war that began in 2001 to root out the Al-Qaeda that carried out the 9/11 attack on the US, and the Taliban than allowed to operate from Afghanistan, has claimed about 2,350 US lives and left more than 20,000 wounded.

Trump had promised in his 2016 campaign to bring all US troops home.

The troops remaining in Afghanistan and Iraq are to defend the US diplomatic and other facilities there.

There was a confluence of views between Trump and some Democratic leaders and opposition from Republicans and the NATO.

The House of Representatives Armed Services Committee Chair Adam Smith, a Democrat, said, “Reducing our forward deployed footprint in Afghanistan down to 2,500 troops is the right policy decision. At the same time, this reduction must be responsibly and carefully executed to ensure stability in the region.”

But the committee's Republican leader Mac Thornberry warned Trump, “These additional reductions of American troops from terrorist areas are a mistake.”

“Further reductions in Afghanistan will also undercut negotiations there; the Taliban has done nothing – met no condition – that would justify this cut,” he added.

The peace agreement with the Taliban, which was seen as a precondition for troop withdrawal, has yet to materialise and the terrorist group has continued attacks in Afghanistan.

Price of troop withdrawal 

“The price for leaving too soon or in an uncoordinated way could be very high,” NATO Secretary-General Jens Stoltenberg said in Brussels.

He warned that Afghanistan risks becoming again the centre of international terror with the Islamic State (ISIS) moving there to rebuild “the terror caliphate it lost in Syria and Iraq.”

While Biden has committed to end the “forever wars in Afghanistan and the Middle East” and to “narrowly focus our mission on Al-Qaeda and ISIS,” neither he nor his transition team has reacted to the preemptive move by Trump.

Trump's action would make policy-making and implementation difficult as soon as he takes over. It is compounded by him and his transition team being cut out of briefings and denied access to officials and information.

As vice president, Biden had been sceptical of his President Barack Obama's troop surge in Afghanistan, when the force-strength was increased from about 30,000 when he assumed office in 2009 to nearly 100,000 in about a year as he attempted to decisively crush the terrorists in hope of a pullout.

Pakistan's leverage

Pakistan has been a key figure in the region, playing all sides. It has benefited from the US invasion of Afghanistan after the 2001 attacks on the US the Al-Qaeda, which was protected by the Taliban and Islamabad, which gave that group's leader Osama Bin Laden asylum.

Pakistan Prime Minister Imran Khan visited Kabul for the first time on Thursday - a visit Afghan President Ashraf Ghani termed as "historic" - a day after the US announced the troop cutback, but according to reports did not say anything about it.

The US-backed Kabul government has been suspicious of and critical of Pakistan for its backing of the Taliban. 

But now Ghani will have to come to terms with Islamabad, which had facilitated the peace between the Taliban and the US, with nominal participation of the Kabul government in the process.

As the patron of the Taliban,  Pakistan will wield more direct influence over Afghanistan as Washington winds down its involvement.

But on the other hand, when the US involvement is minimised and troops are no longer active beyond the protection of US resources, Islamabad's leverage is also reduced because US troops would no longer be vulnerable to cross-border terrorism and terror attacks by Pakistan's proxies and therefore will not have to be deferential to it.

Nor would Islamabad be able to exert influence by manipulating Taliban diplomacy.

The danger for Pakistan and the world will be the rise of the ISIS in an Afghan vacuum. Islamic State’s Khorasan Province (ISIS-K) group has been a threat to both Afghanistan and Pakistan and Islamabad will have to contain it and similar groups for its own protection – and not make a deal with them lest it face a backlash from the US.

There has been no signs of opposition in the Pentagon to the troop withdrawal.

(The writer is Nonresident Fellow, Society for Policy Studies - SPS. Views expressed are personal)