country's nuclear deal with the u.s. and its allies. ayatollah kmhamenei is calling for vigilance, saying the u.s. cannot be trusted. his approval is essentially the final word in iran on the issue. while the bombs continue to fall in syria, diplomatic efforts to end that country's civil war are accelerating tonight. syria's embattled leader took a rare trip to moscow, while america's top diplomat is scheduled to meet with his russian counterpart on friday. correspondent kevin corke has the latest from the white house. >> it was a long-awaited meeting between long-time allies, as syrian president bashar al assad and russian president vladimir putin greeted each other tuesday in moscow. assad's first trip outside of his war-torn country since 2011. >> i thank you for standing up for syria's unity and its independence. >> for putin, the meeting comes at a crucial moment at the war in syria armed with the syrian government's approval to launch