The Taliban has welcomed news of the US plan to withdraw half its troops from Afghanistan by the summer, as Afghan generals warned it would be a blow to the morale of the country’s beleaguered security forces.

The announcement seems certain to complicate efforts to reach a peace deal, mostly because it gives the Taliban leverage by allowing them to hold off until a total US withdrawal, or step up their demands over a weakened Afghan government.

Afghanistan’s security forces rely heavily on US air power against both the Taliban and an upstart Islamic State affiliate, and Afghan military officials noted the announcement by the Trump administration comes as the country’s security is at its worst since 2014.

In that year, more than 100,000 Nato troops pulled out of the country and handed off security to Afghans. The US and Nato retreated into a training and advising role.

Bill Roggio, an Afghanistan analyst with the US-based Foundation for Defence of Democracies, said: “A complete withdrawal of US forces would very likely cause the Taliban to make gains in key areas throughout Afghanistan.

“This likely would cause the general collapse of the (Afghan National Security and Defence Force) as a cohesive fighting force and lead to the return of the warlords.”

But the Taliban said the withdrawal could in fact assist peace efforts by helping to build trust.

(PA Graphics)

President Donald Trump considers the war in Afghanistan a lost cause and has long pushed to pull the troops out. His decision was made public a mere few hours after he abruptly announced the US was withdrawing troops from Syria.

Mr Trump’s state of mind is sure to have given a sense of urgency to US peace envoy Zalmay Khalilzad, who has been working to reach a negotiated end to America’s longest war and has been pushing for a deal by April.

In an interview with Afghanistan’s TOLO TV on Thursday – hours before the withdrawal plans were announced – he noted Mr Trump had campaigned for president on a promise to end the Afghan war, which has already cost Americans nearly 1 trillion US dollars. More than 2,400 American soldiers have died in Afghanistan since the 2001 invasion.

A Taliban official said the announcement is a positive step which could “lead to trust building that the US wants a political solution”.

But there is no sign the Taliban are ready to move on the two major sticking points: Direct talks with the Afghan government and a ceasefire while the two sides negotiate Mr Khalilzad’s so-called “roadmap for the future of Afghanistan”.

Zalmay KhalilzadZalmay Khalilzad has been trying to reach a peace settlement in Afghanistan (Rafiq Maqbool/AP)

Peace talks aside, the announced withdrawal has Afghan generals and analysts worried about the ability of the beleaguered Afghan National Afghan Security Force to stave off a Taliban insurgency unfettered by US troops and their pounding air power.

The Taliban are already stronger today than they have been since they were ousted in 2001, controlling or holding sway over nearly half the country.

Several high ranking Afghan military officials said the morale of Afghanistan’s under-trained and poorly equipped security forces is already at a dangerously low ebb. The troops routinely complain about reinforcements that arrive too late, equipment that fails and even running out of food.

The officials called America’s withdrawal a defeat, comparing it to the US evacuation from Vietnam and Russia’s 1989 forced withdrawal from Afghanistan that capped a failed 10-year campaign.