The U.S. Air Force has deployed an upgraded version of the country's largest non-nuclear bomb — a 30,000-pound "bunker-buster" that can only be carried by the B-2 stealth bomber and could be used against adversaries such as North Korea.
A fourth upgrade to the Boeing Co. bomb, the GBU-57, has been completed and the existing inventory is being retrofitted, Capt. Emily Grabowski, an Air Force spokeswoman, said in an email. The modification "has improved the performance against hard and deeply buried targets," she said.
Bombs known as bunker-busters have been in the air force's arsenal for years for potential attacks against buried targets. The GBU-57, which is six times bigger than the 5,000-pound bomb the air force has had for years, could be used if the U.S. decided to hit underground nuclear or missile facilities in North Korea, as tensions persist over Kim Jong Un's growing nuclear arsenal.