Afghanistan's Taliban insurgents have not yet met the conditions for a complete withdrawal of US troops from the country under the deal they signed with Washington, the commander overseeing US forces there said. Gen Frank McKenzie, head of US Central Command, said the US was ahead of schedule for an initial drawdown to 8,600 troops by July. Another US official, who spoke on condition of anonymity, said troop levels were now below 9,000, compared with about 12,000 in February. The US-Taliban deal signed in February envisions all American troops leaving Afghanistan by May 2021, but Gen McKenzie stressed that this was dependent on conditions. "Those conditions would be: can we be assured that attacks against us will not be generated there? And as of right now ... frankly, if asked my opinion, those conditions have not been fully met,” he said in a video conference hosted by the Middle East Institute in Washington. The Centcom chief spoke from his headquarters in Florida. Gen McKenzie's scepticism comes as President Donald Trump focuses on an early troop exit that would fulfill his frequent promise to get the United States out of Afghanistan. Mr Trump has said US troops are acting as police in Afghanistan and should get out of a conflict that is now almost two decades old. In late May, Mr Trump called for a quick return of American soldiers and urged Afghan forces to step up in the defence of their country. He tweeted: “Bring our soldiers back home but closely watch what is going on and strike with a thunder like never before, if necessary!” Mr Trump has often complained about the enormous cost of the war, which began in October 2001 with a US invasion to topple the Taliban from power. The president's impatience, and speculation that he may order that all US troops leave by the November election, has caused some angst on Capitol Hill. Four members of the Senate Intelligence Committee, including the panel's vice chairman, Democrat Mark Warner of Virginia, wrote on Tuesday to the director of national intelligence, John Ratcliffe, asking that he provide an update on intelligence planning for Afghanistan if a decision is made to pull out by November. “A rushed and premature withdrawal would also risk losing the gains we have achieved in Afghanistan, not only in counterterrorism but also in building Afghan governance and military forces,” they wrote. “Our nation’s intelligence professionals have spent nearly two decades establishing security arrangements with our Afghan partners. Now it is incumbent upon our government to give them the time and space to prepare for an orderly, conditions-based drawdown, in conjunction with military and diplomatic counterparts.” The Taliban had provided sanctuary for Al Qaeda, which used Afghanistan as a base for plotting the 9/11 attacks. “The threat to the United States is not the Taliban. It has never been the Taliban,” Gen McKenzie said. “It's the entities that they allow to live in Afghanistan that threaten us.” He mentioned the Afghan affiliate of ISIS and Al Qaeda. “We believe the Taliban actually are no friends of ISIS and work against them,” he said. “It is less clear to me that they will take the same action against Al Qaeda.” Gen McKenzie said the Trump administration was engaged in “very robust dialogue” internally and with Nato and coalition partners “as we evaluate the way forward” in Afghanistan.