Israel launched an attack on Iranian soil on Friday, sources said, in the latest tit-for-tat exchange between the two arch foes, whose decades of shadow war has broken out into the open and threatened to drag the region deeper into conflict, writes Reuters.

Iranian media reported explosions, but an Iranian official told Reuters those were caused by air defense systems. State media said three drones over the central city of Isfahan had been shot down.

Israel’s leadership and the military were silent early on Friday. Iran has no plan to strike back immediately, a senior Iranian official told Reuters, while state media had an initially subdued response to the attack.

The United States received notification before Israel’s attack, a source familiar with the situation told Reuters, which came days after Iran launched an unprecedented strike, opens new tab on Israel with a barrage of drones and missiles. Most of those were shot down.

Washington and other global powers had pressed Israel not to respond, or to ensure any further retaliation, opens new tab was limited to prevent a broader conflagration after the latest surge in violence was sparked by the air strike on the Iranian embassy compound in Damascus on April 1 that was blamed on Israel.