WASHINGTON, Aug 28 (Reuters) - U.S. President Joe Biden on Saturday promised further strikes against the Islamic State in Afghanistan in retaliation for a deadly bombing outside Kabul airport and warned that the situation on the ground continued to be "extremely dangerous." "This strike was not the last. We will continue to hunt down any person involved in that heinous attack and make them pay," Biden said in a statement. "Our commanders informed me that an attack is highly likely in the next 24-36 hours. I directed them to take every possible measure to prioritize force protection."