Israel’s unprecedented attacks on Iran had at their core an elusive and high-risk goal: eradicating the country’s controversial nuclear program. Israel targeted three key Iranian nuclear facilities – Natanz,

Iran has two known underground nuclear enrichment sites, the one Israel attacked on the first day of its assault at Natanz, and another at Fordo. Both sit south of Tehran in central Iran, but Fordo has long been the Iranian nuclear facility of most concern to international monitors and experts.

Israel stunned Iran last week with an intelligence and military operation years in the making that struck high-level targets with precision.

The Fordow facility is home to thousands of centrifuges, crucial to Iran’s weapons-grade uranium enrichment program, and is located 295 feet underground beneath a mountain. Israel is thought to have neither the munitions nor the aircraft to destroy it from the air, while the U.S. does .