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 strikes Iran's nuclear facilities, but an expert cautions that the heavily protected Fordow site remains a dangerous threat that only U.S. military capabilities can neutralize.

Israeli strikes on Natanz, Fordow and Isfahan pose little regional radiation risk but could release plumes of toxic chemicals, experts said.

Israel has escalated its bombardment of Iranian cities, including Tehran's state television headquarters; Iranian missiles have struck Tel Aviv.

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,

The U.S. is considering targeting Iran's uranium enrichment facility at Fordo, five sources familiar with the matter told CBS News.

An Israeli official said that "there's never a 100 percent guarantee," but "a nuclear disaster" should "not happen."

Kyle Bass, Hayman Capital Management founder and CIO, joins 'Squawk Box' to discuss the latest developments in the Israel-Iran conflict, America's role in the conflict, and more.