Israel's sweeping attack across Iran struck at the heart of Tehran's nuclear program, delivering a blow to the country's ability to enrich uranium and potentially setting its nuclear ambitions back by months or years.

Israel attacked Iran early Friday and killed many of the country’s top military leaders and scientists. Iran retaliated with missiles and drones.

Before Israel launched a wave of strikes against Iran’s nuclear facilities and top military leaders this week, its spies were already on the ground in enemy territory.