The US just dropped the mother of all bombs on ISIS in Afghanistan - here's what that means

The US dropped a massive, 22,000-pound bomb for the first time ever on entrenched ISIS targets in Afghanistan on Thursday, according to the Pentagon.

"At 7:32 pm local time today, U.S. Forces - Afghanistan conducted a strike on an ISIS-K tunnel complex in Achin district, Nangarhar province, Afghanistan, as part of ongoing efforts to defeat ISIS-K in Afghanistan in 2017," US Central Command said in a statement.

"The whole point of the MOAB (Massive ordnance air blast, AKA Mother of all bombs) is that it causes over-pressure," Dr. Adam Lowther, director of the US Air Force's school of deterrence told Business Insider in a phone interview.

That overpressure, caused by the bomb detonating at a low altitude over the target, crushes underground tunnels and bunkers, like the kind often employed by ISIS.

While it's the first use of the US's biggest non-nuclear bomb, Lowther said that it's "not even close to being a nuclear weapon" and he would "not make the argument that it's a symbol of escalation" in the conflict in Afghanistan.

For comparison, the nuclear bombs dropped on Hiroshima and Nagasaki during World War II had an explosive yield of about 15 kilotons. Lowther says the MOAB doesn't even come close, at 0.1 or 0.2 kilotons.