Iran has launched hundreds of aerial drones and missiles at Israel, marking a widely anticipated reprisal attack.
It is the first such direct clash between the two enemies, who have been engaged in a years-long shadow war, with Iran using proxy forces.
The Israeli military said Israel and other countries had intercepted more than 300 cruise missiles and drones, mostly outside Israeli airspace.
Israel said very little damage had been done but warned people to remain alert.
US President Joe Biden said “we helped Israel take down nearly all” of missiles and drones as he expressed strong condemnation for the attack.
“Iran and its proxies operating out of Yemen, Syria and Iraq launched an unprecedented air attack against military facilities in Israel,” he said.
Iran’s Islamic Revolution Guard Corps (IRGC) said the attack was aimed at “specific targets”.
Iran had vowed to retaliate for a strike on its consulate in Syria on 1 April which killed seven IRGC officers, including a top commander. It accused Israel of carrying out that attack, but Israel neither confirmed nor denied it.