Each B-2 can carry two 30,000-pound GBU-57s, known as MOPs. The bombs are designed to detonate in a series of explosions to collapse multi-level structures buried underground.

Air traffic control communications indicated that several B-2 aircraft — the planes that could be equipped to carry the 30,000-pound bunker-buster bombs that Mr. Trump is considering deploying against Iran's underground nuclear facilities in Fordo — had taken off from Whiteman Air Force Base in Missouri.

The US used six B-2 bombers to drop a dozen “bunker buster” bombs on the Fordow nuclear site in Iran, a US official told CNN. Navy submarines fired 30 TLAM cruise missiles at two other sites, Natanz and Isfahan, and a B2 dropped two bunker busters on Natanz, the official said.