An Afghan government defence official said Sunday that a deal over Bagram air base was "not possible", after US President Donald Trump said he wanted the former US base back. Bagram, the largest air base in Afghanistan located north of the capital Kabul, was the centre of US operations in their 20 year-war against the Taliban. "If Afghanistan doesn't give Bagram Airbase back to those that built it, the United States of America, BAD THINGS ARE GOING TO HAPPEN!!!" "Recently, some people have said that they have entered negotiations with Afghanistan for taking back Bagram air base," he said in comments broadcast by local media. The loss of crucial air power saw the Afghan military collapse just weeks later and the Taliban sweep back to power.