AMMAN/JERUSALEM (Reuters) - Syrian rebels and a U.S. official cited by CNN said on Thursday Israel had mounted a new attack on a Syrian military base but the Israeli government declined to confirm any strike. CNN quoted an unidentified U.S. administration official on Thursday as saying Israeli warplanes struck a Syrian base near the port of Latakia, targeting missiles that Israel thought might be transferred to its Lebanese militia enemy Hezbollah. One Syrian opposition source, a defector from air force intelligence with contacts in the Latakia region, said Israel struck a strategic missile battery near a village called Ain Shikak where President Bashar al-Assad's forces kept long-range Russian missiles that are among their most powerful weapons.