The US missile attack caused heavy damage to one of Syria's biggest and most strategic air bases - but the impact on President Bashar Assad's military capabilities is limited.

A Russian transport helicopter was shot down in opposition rebel territory in northern Syria yesterday and all five crew and officers onboard were killed, the Kremlin said. 

In a move raising the potential threat of a Russia-NATO conflict, Russia says it will deploy long-range air defence missiles to its base in Syria and destroy any target that may threaten its warplanes after the downing of its military jet by Turkey.