A missile launched from Syria struck Israel's Negev desert region early Thursday, setting off air raid sirens near the country's top-secret nuclear reactor, the Israeli military said.
In response, it said it struck the missile launcher and other targets in neighbouring Syria.
The incident, marking the most serious violence between Israel and Syria in years, pointed to likely Iranian involvement.
Iran, which maintains troops and proxies in Syria, has accused Israel of a series of attacks on its nuclear facilities, including a recent fire at its Natanz nuclear facility, and vowed revenge.
The Israeli army said the missile landed in the Negev region and the air raid sirens were sounded in a village near Dimona, where Israel's nuclear reactor is located.
There was no word on whether anything had been struck, but explosions were reported across Israel.
Israel and Iran are arch-enemies. Israel accuses Iran of trying to develop nuclear weapons and has opposed US-led efforts to revive the international nuclear deal with Iran.
Israel's government says the deal will not prevent Iran from developing a nuclear weapons capability. It also says it does not address Iran's long-range missile programme and its support for hostile proxies in Lebanon, Syria and Gaza.
Iran says its nuclear programme is for peaceful purposes only, and has noted that Israel is widely believed to have a nuclear weapons program in Dimona.
Israel neither confirms nor denies claims it has nuclear weapons.
