In August, Yuval Steinitz, Israel’s minister for international affairs, strategy, and intelligence, claimed that Iran’s uranium-enrichment facilities can be “destroyed with brute force,” which he described as “a few hours of airstrikes, no more.” Yaakov Amidror, who recently stepped down as national security advisor, asserted this month that Israel can “stop the Iranians for a very long time.” Asked whether this includes Iran’s deeply buried nuclear installations, he responded, “including everything.”

Most U.S. government and nongovernmental experts in weaponeering effects disagree with Amidror. They have concluded that Israel’s conventional air-dropped bombs cannot penetrate the bedrock to reliably destroy the centrifuges located within Fordow. Moreover, both George W. Bush’s and Barack Obama’s administrations have refused to provide Israel with the Pentagon’s largest (and recently further improved) conventional bunker-buster bomb, the Massive Ordnance Penetrator. Respected defense reporter David Fulghum quoted an anonymous U.S. defense specialist as saying, “Right now the Israeli capability against deeply buried targets is not much more than a noise-level effect.” Given Israel’s inability to deliver what one U.S. official termed “a knockout blow” against well-defended nuclear sites like Fordow with conventional bombs, a low-yield nuclear weapon could be the only viable alternative for a unilateral Israeli strike.