Israel had been looking for a chance to kill the leader of Hezbollah.

Its intelligence had long tracked Hassan Nasrallah and it recently learned he planned to move, which would have closed the window of opportunity, according to a senior official who asked not to be identified discussing confidential matters. Prime Minister Benjamin Netanyahu gave the order Friday from his hotel room in New York, just before giving a fiery speech to the United Nations General Assembly that rejected a U.S.-backed push for a ceasefire in Lebanon.

Washington, Israel’s closest ally, got only a last-minute heads up as its latest bid to stop the violence failed. Friday’s strike in southern Beirut was another in a series of dramatic Israeli attacks — from exploding pagers to sweeping air raids — that have left Iran’s main proxy severely debilitated and now leaderless.