Israel has threatened to destroy Syrian air defence systems after they fired ground-to-air missiles at Israeli warplanes carrying out strikes. Israeli Defence Minister Avigdor Lieberman today said on public radio that the next time the Syrians use their air defence systems against Israeli planes they will destroy them without the slightest hesitation.<br/><br/>Israeli warplanes hit several targets in Syria on Friday, with Prime Minister Benjamin Netanyahu saying the strikes targeted weapons bound for Lebanon's Shia Hezbollah movement. <br/><br/>Syria's military said it had downed one of the Israeli planes and hit another as they were carrying out the pre-dawn strikes near the famed desert city of Palmyra that it recaptured from extremists this month.<br/><br/>However, the Israeli military denied that any planes had been hit. Reports say, it was the most serious incident between the two countries since the Syrian civil war began six years ago.