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.

If the U.S. decides to support Israel more directly in its attack on Iran, one option for Washington would be to provide the “bunker-buster” bombs believed necessary to significantly damage the Fordo nuclear fuel enrichment plant,