Israel launched a blistering attack on the heart of Iran’s nuclear and military structure Friday, deploying warplanes and drones smuggled into the country to target key facilities and kill top generals and scientists -- a barrage it said was necessary before its adversary got any closer to building an atomic weapon. The ongoing military and intelligence operation raised the potential for all-out war between the countries and propelled the region, already on edge, into even greater upheaval. Iran quickly retaliated by sending a swarm of drones at Israel, and Supreme Leader Ayatollah Ali Khamenei warned of “severe punishment.” Iran had been censured by the U.N.’s atomic watchdog a day earlier for not complying with obligations meant to prevent it from developing a nuclear weapon. Israel had long threatened such a strike, and successive American administrations had sought to prevent it, fearing it would ignite a wider conflict across the Middle East and possibly be ineffective at destroying Iran’s dispersed and hardened nuclear program. But a confluence of developments triggered by Hamas’ Oct. 7, 2023, attack — plus the reelection of U.S. President Donald Trump — created the conditions that allowed Israel to finally follow through on its threats. Israel had told the Trump administration that the large-scale attacks were coming, officials in the U.S. and Israel said on condition of anonymity to describe private diplomatic discussions. On Wednesday, the U.S. pulled some American diplomats from Iraq’s capital and offered voluntary evacuations for the families of U.S. troops in the wider Middle East. On Friday, the U.S. began shifting military resources in the region, including ships, as Israel prepared for more retaliation, two U.S. officials said. Countries in the region condemned Israel's attack, while leaders around the globe called for immediate deescalation from both sides. The U.N. Security Council scheduled an emergency meeting for Friday afternoon at Iran's request. In a letter to the council, Iran’s Foreign Minister Abbas Araghchi called the killing of its officials and scientists “state terrorism" and affirmed his country's right to self-defense. “Israel will come to deeply regret this reckless aggression and the grave strategic miscalculation it has made,” he said. Israel's military said about 200 aircraft were involved in the initial attack on about 100 targets. Its Mossad spy agency positioned explosive drones and precision weapons inside Iran ahead of time, and used them to target Iranian air defenses and missile launchers near Tehran, according to two security officials who spoke on condition of anonymity. It was not possible to independently confirm the officials' claims. Among the key sites Israel attacked was Iran's main nuclear enrichment facility at Natanz, where black smoke could be seen rising into the air. Israel also said it destroyed dozens of radar installations and surface-to-air missile launchers in western Iran. Israel military spokesman Brig. Gen. Effie Defrin said the Natanz facility was “significantly damaged” and that the operation was “still in the beginning.” The first wave of strikes had given Israel “significant freedom of movement” in Iran’s skies, clearing the way for further attacks, according to an Israeli military official who spoke on condition of anonymity because he was not authorized to discuss details of the attack with the media.