The extent of Iran's support for the Assad regime was exposed earlier this month when 48 Iranians were captured and taken hostage by Syrian opposition fighters. The Iranians, who are said to include senior Revolutionary Guard officers, claimed they were conducting "reconnaissance missions", and their capture by Syrian opposition fighters was deeply embarrassing for Tehran, which is demanding their immediate safe return to Iran. Syrian rebels have threatened to kill the hostages unless Iran ends its support for the Assad regime.