US official: 4 Russian missiles flopped in Iran

Moscow denies report, claiming its airstrikes targeting Syrian rebels all 'hit their target'

Four Russian cruise missiles aimed at targets in Syria crashed in Iran, a US official said on Thursday, as Syrian troops pressed a "vast offensive" against rebels in the war-torn country's west.

The missiles were said to be part of a salvo fired on Wednesday from Russian warships in the Caspian Sea as part of the nine-day-old military initiative targeting foes of the Syrian government.