The Taliban have denounced the new American plan for troops to quit the country by September 11, saying it breaches an earlier agreement negotiated with Donald Trump. Joe Biden's decision to leave America's longest war before the symbolic anniversary of the 9/11 attacks, rather than May 1 as agreed under Mr Trump , will justify “countermeasures” the insurgent movement said. The hardline Islamist militants made their first official response to Mr Biden's announcement of an unconditional withdrawal, as America's top diplomat visited Kabul to try to sell the pull out. A statement from the insurgents said that “delaying the withdrawal date of forces by several months, all makes evident to the world that America cannot be trusted nor is it committed to its pledges and promises.” It went on: “Now as the agreement is being breached by America, it in principle opens the way for the Mujahideen of Islamic Emirate to take every necessary countermeasure, hence the American side will be held responsible for all future consequences, and not the Islamic Emirate.” Joe Biden confirmed earlier this week that he would pull troops out of Afghanistan 20 years after they first arrived to topple the Taliban regime harbouring Osama bin Laden. Mr Biden's secretary of state, Antony Blinken, flew to Kabul on Thursday to show support for the Afghan government hours after the White House had announced an unconditional withdrawal. Ashraf Ghani's government is heavily reliant on American support in the face of the Taliban, but has claimed it can stand without US troops. Mr Blinken tried to reassure Mr Ghani that the United States would remain committed to Afghanistan, saying Washington will "intensify" its diplomacy to do "everything we can" to advance efforts to secure a peace agreement between Kabul and the insurgents. "The reason I'm here, so quickly after the president’s speech last night, is to demonstrate literally, by our presence, that we have an enduring an ongoing commitment to Afghanistan," he said.