WASHINGTON (AP) — In a horrifying act of revenge for U.S. airstrikes in northern Iraq, militants with the Islamic State extremist group have beheaded American journalist James Foley — and are threatening to kill another hostage, U.S. officials say. The car he was riding in was stopped by four militants in a contested battle zone that both Sunni rebel fighters and government forces were trying to control. Both areas are in northern Iraq, which has become a key front for the Islamic State as its fighters travel to and from Syria. Since Aug.