Israeli warplanes struck several targets inside Syria overnight Tuesday, including a biological weapons research center that was reportedly flattened out of concern that it might fall into the hands of Islamist extremists fighting to topple the government of Syrian president Bashar Assad, Western intelligence officials tell TIME.

So far only two airstrikes have been publicly reported, amid a flurry of conflicting initial reports. Syria officially complained of the destruction of the Scientific Studies and Research Center in Jamarya northwest of Damascus. And a variety of news organizations reported that Israeli jets hit a convoy carrying advanced anti-aircraft defense systems toward Lebanon’s Bakaa Valley, presumably for delivery to Hizballah, the militant Shi’ite group closely allied with the Assad regime. If they had been deployed, those SA-17 ground-to-air missiles would intimidated Israeli pilots who now operate over Lebanese airspace with impunity, forcing them to higher altitudes and other operational precautions.

A Western intelligence official indicated to TIME that at least one to two additional targets were hit the same night, without offering details. Officials also said that Israel had a “green light” from Washington to launch yet more such strikes.