Buster.

This is coolbert:

As extracted from the web site isegoria.net and thanks to same.

The bunker busting bomb. Being used right now by Israeli combat aviation missions the Gaza War?

"Drop a howitzer on them"

From https://www.isegoria.net | November 22 2023.

"The GBU-28 is a 5,000-pound laser-guided 'bunker busting' bomb"

"It was designed, manufactured, and deployed in less than three weeks due to an urgent need during Operation Desert Storm to penetrate hardened Iraqi command centers located deep underground."

See the wiki entry https://en.m.wikipedia.org/wiki/GBU-28

"The initial batch of GBU-28s was built from modified 8 inch/203 mm artillery barrels (principally from deactivated M110 howitzers), but later examples are purpose-built with the BLU-113 bomb body made by National Forge of Irvine, Pennsylvania. They weigh 5,000 pounds (2,268 kg) and contain 630 pounds (286 kg) of Tritonal explosive."

Ratio of the explosive bang-stuff to the overall weight of the bomb rather low. Slightly greater than 10 % only! A bunker-buster bomb obviously needs a casing armor-piercing very heavy and of stout manufacture. 

Three weeks only from design to deployment? Just shows the USA military can do what it wants if it decides to do so, project not impeded by red-tape or excessive bureaucracy!

coolbert.