Iran's Fordow nuclear site

A bunker buster is a broad term used to describe bombs that are designed to penetrate deep underground before detonating. The US-made Massive Ordnance Penetrator (MOP), officially known as GBU-57 A/B, is the world's most powerful non-nuclear bunker buster.

It is much larger than earlier USAF weapons designed to destroy heavily fortified, deep underground bunkers such as the 5,000-pound (2,300 kg) GBU-28 and GBU-37. The B-2 Spirit strategic bomber is the only in-service U.S. aircraft that can carry the heavy 20.5-foot (6.2 m)-long weapon.

The GBU-28 (Guided Bomb Unit‐28) is a 4,000–5,000-pound (1,800–2,300 kg) class laser-guided "bunker busting" bomb produced originally by the Watervliet Arsenal, Watervliet, New York.