A U.S. attack on Iran's key underground nuclear facility would not be a guaranteed success, according to a national security expert.

The Fordo nuclear facility is Iran's most heavily fortified uranium enrichment facility and an increasingly high-priority target for Israeli attacks

The Israeli military does not possess the necessary means to destroy the uranium enrichment facilities at the underground Fordo site. The American GBU-57, a highly powerful bunker-busting bomb, was specifically designed for that purpose.