Iran fired air defenses at a major air base and a nuclear site early Friday morning (Apr. 19) near the city of Isfahan after spotting drones, which Iranian authorities claim were part of Israel's retaliation over Tehran's unprecedented attack last week. 

While no Iranian official directly acknowledged the possibility that Israel attacked, and the Israeli military did not respond to a request for comment, tensions have been high since the Saturday assault on Israel amid its war on Hamas in Gaza and its own strikes targeting Iran in Syria, the Associated Press reported.

US officials declined to comment as of early Friday, but American broadcast networks quoted unnamed US officials saying that Israel carried out the attack. 

The New York Times quoted anonymous Israeli officials claiming the assault, which came on Iranian Supreme Leader Ayatollah Ali Khamenei's 85th birthday. Israeli politicians also made comments hinting that the country had launched an attack.

"The explosion this morning in the sky of Isfahan was related to the shooting of air defense systems at a suspicious object that did not cause any damage," Iranian army commander Gen. Abdolrahim Mousavi said. 

It could not be independently verified what kind of drone flew over Iran.