WASHINGTON (AP) — Defense Secretary Jim Mattis is warning against dangerous flights by Russian fighter jets over what is considered a safe zone in Syria, questioning whether recent close calls were mistakes or deliberate. Mattis tells Pentagon reporters that the U.S. and Russia are still using a phone line to coordinate flight movements over crowded Syrian skies as the U.S.-led coalition goes after remaining Islamic State group militants. Two Russian Su-25 fighters flew through an unofficial line separating Russian and American air forces in eastern Syria on Wednesday coming dangerously close to U.S.