Israeli embassies and major Jewish institutions around the world raised their levels of alert on Sunday over fears of terror attacks by Iran and Hezbollah in retaliation for reported Israeli airstrikes on Iranian missiles in Syria.

“Everywhere there is an Iranian embassy, there is usually one person, and probably more, directly involved in planning terrorist activity against Jewish and Israeli targets,” Brig. Gen. (Res.) Nitzan Nuriel, the former head of the Israeli National Security Council’s counter-terrorism bureau, told Army Radio. “Sometimes it’s under the cover of a cultural attache or even just a normal staffer, but these people are tasked with perpetrating terror against Israel and Jews.”

The Israel Defense Forces on Sunday closed off the airspace over northern Israel to civilian flights, but the airspace was reopened on Monday. Flights on the Haifa-Eilat route of the Arkia and Israir airlines were canceled.