FILE PHOTO: Youths take pictures next to an Afghan flag on a hilltop overlooking Kabul, Afghanistan, April 15, 2021. REUTERS/Mohammad Ismail/File Photo KABUL (Reuters) - U.S. President Joe Biden's announced pullout of troops from Afghanistan by Sept. 11 has jeopardised Washington's push for peace with Taliban Islamists and increased the chances of an upsurge in violence, sources say. Biden announced the withdrawal, pushed back from a May 1 deadline agreed with the Taliban, without buy-in from the insurgents, sources involved in the discussions told Reuters. The decision was signalled just hours after Turkey announced dates for a crucial peace summit on April 24, which the Taliban had also not yet agreed on.