Israel has carried out a series of air strikes on Iran, targeting military facilities, nuclear sites and residential areas of the capital, Tehran, and killing at least two senior military commanders and top nuclear scientists.

The strikes early on Friday come amid simmering tensions over Iran’s nuclear programme and appeared certain to trigger a reprisal. Supreme Leader Ali Khamenei warned that “severe punishment” would be directed at Israel. Hours later, Israel’s military said it had begun intercepting Iranian drones launched in retaliation.

An Israeli official said the interceptions were taking place outside Israeli territory but did not elaborate. The official spoke on the condition of anonymity, pending a formal announcement.