Explainer: How powerful is the U.S.' GBU-57 'bunker buster' bomb?

On Saturday, U.S. President Donald Trump announced that the U.S. military had completed "very successful" attacks on three nuclear sites in Iran, including Fordow, Natanz and Isfahan, saying a "full payload" of bombs had been dropped on the primary site, the Fordow facility.

Six bunker buster bombs were used in the attack on Fordow, and 30 Tomahawk missiles targeted other Iranian nuclear facilities, China Media Group (CMG) reported.

U.S. B-2 Spirit stealth bombers were also involved in the strikes, said a U.S. official.

What is a bunker buster bomb?

The term "bunker buster" refers to bombs specifically designed to penetrate deep underground targets before detonating. In this case, it refers to the latest GBU-57 A/B Massive Ordnance Penetrator (MOP) bomb in the American arsenal.

Weighing about 13.6 tonnes and measuring around 6 meters in length, the GBU-57 MOP bomb is believed to be the world's "most powerful bomb," second only to nuclear weapons.

It can penetrate about 61 meters below the surface before exploding. Equipped with an advanced navigation system, the GBU-57 can be dropped in quick succession, effectively drilling deeper and deeper to destroy deeply buried, hardened facilities.

The Fordow facility, located deep underground, was believed to be beyond the reach of conventional bombs, including those used by Israel. Media reported that the U.S. GBU-57 MOP is the only bomb in the U.S. arsenal capable of destroying the facility.

The U.S. B-2 bomber is currently the only aircraft that can carry and deploy the GBU-57 in combat, and each B-2 is capable of carrying two GBU-57 bombs simultaneously.