LONDON—The U.S. government is unlikely to extend the evacuation window to allow its citizens and Afghans more time to fly out of Kabul, British defence minister Ben Wallace said ahead of emergency talks by G7 leaders. U.S. President Joe Biden will face pressure to extend an Aug. 31 deadline to evacuate thousands seeking to flee the Taliban in Afghanistan at a virtual meeting of the leaders of the Group of Seven wealthy nations on Tuesday. The Taliban have said they will reject any demands by Western forces to extend the deadline to allow more time to complete the evacuation operation. Biden said on Sunday that he would not like to extend the deadline, but that talks were ongoing. “I think it is unlikely,” Wallace told Sky News. “Not only because of what the Taliban has said but also if you look at the public statements of President Biden.” He added: …