WASHINGTON, United States (AFP) — US President Donald Trump on Saturday threatened Afghanistan with unspecified punishment if the Taliban-controlled country did not "give Bagram Airbase back."

"If Afghanistan doesn't give Bagram Airbase back to those that built it, the United States of America, BAD THINGS ARE GOING TO HAPPEN!!!" the 79-year-old leader wrote on his Truth Social platform.

The vague threat came just days after he raised the idea of the US retaking control of the base while on a state visit to the United Kingdom.

Bagram, the largest air base in Afghanistan, was a linchpin of the US-led war effort against the Taliban, whose government Washington toppled following the 11 September 2001 attacks on the US.

An Afghan government defence official said Sunday that a deal over Bagram air base was "not possible."

"Recently, some people have said that they have entered negotiations with Afghanistan for taking back Bagram air base," Fasihuddin Fitrat, chief of staff of Afghanistan's ministry of defense, said in comments broadcast by local media.

"A deal over even an inch of Afghanistan's soil is not possible. We don't need it."

Later in an official statement, the Afghan government said that "Afghanistan's independence and territorial integrity are of the utmost importance."

Trump has often lamented the loss of access to Bagram, noting its proximity to China, but Thursday was the first time he has made public that he was working on the matter.

"We're trying to get it back, by the way, that could be a little breaking news. We're trying to get it back because they need things from us," Trump said at a press conference with British Prime Minister Keir Starmer.

US and North Atlantic Treaty Organization troops chaotically pulled out of Bagram in July 2021 as part of a Trump-brokered peace deal, as the resurgent Taliban took over swaths of Afghanistan before finally taking control of the entire country.

Trump has repeatedly criticized the loss of the base since returning to power, linking it to his attacks on his predecessor Joe Biden's handling of the US pullout from Afghanistan.

Trump has also complained about China's growing influence in Afghanistan.

Later on Saturday, the US president was asked by reporters at the White House if he was considering sending US troops to retake Bagram.

"We won't talk about that, but we're talking now to Afghanistan, and we want it back and we want it back soon, right away. And if they don't do it, you're going to find out what I'm going to do," he said.