Israel said on Saturday it had killed a veteran Iranian commander during attacks by both sides in the more than week-long air war, while Tehran said it would not negotiate over its nuclear program while under threat.

Iran’s supreme leader, Ayatollah Ali Khamenei, who crushed internal threats repeatedly during more than three decades in power, now faces his greatest challenge yet. His archenemy, Israel, has secured free rein over Iran’s skies and is decimating the country’s military leadership and nuclear program with its punishing air campaign.