JERUSALEM (Reuters) - An Israeli official played down on Wednesday the Russian upgrading of Syria’s air defences, saying the newly supplied S-300 missile system could be defeated by Israel’s stealth fighters and possibly destroyed on the ground. Moscow said on Tuesday that it had delivered the S-300, a decision it took after accusing Israel of indirect responsibility for the downing of a Russian spy plane by Syrian forces as they fired on attacking Israeli jets last month. Damascus and its big-power backer describe the advanced addition to Syria’s arsenal as a major deterrent. Israel and Washington have both voiced misgivings...