The jets are the only aircraft capable of striking Iran's most heavily-fortified nuclear sites.

Iran's most fortified nuclear facility, called Fordo, is buried deep inside a mountain. Only the U.S. has the 30,000-pound bombs — often referred to as "bunker busters" — capable…

The United States’s B-2 stealth bomber is currently the only aircraft designed to deploy the GBU-57 bunker buster bombs.