The White House is considering using the largest non-nuclear bomb in the US arsenal against Iranian power plants and nuclear facilities if the war with the Islamic Republic resumes.

CNN reports, citing multiple US officials, that President Donald Trump is considering authorizing the use of the GBU-43/B Massive Ordnance Air Blast bomb, or MOAB. The weapon is among the options being considered for strikes on Iranian nuclear sites.

The MOAB is also called the “Mother of All Bombs.” The bomb is a massive 21,000-pound weapon deployed by being pushed from the back of a military transport plane. Unlike the GBU-57 bunker-buster, the MOAB is not designed to penetrate deeply buried facilities. In 2003, military officials told CNN the MOAB was mainly conceived as a weapon employed for “psychological operations.”

Some US officials questioned if the weapon would be effective against Iranian nuclear sites, many of which are buried deep under mountains. “The MOAB is a massive information operation type weapon that is great for huge area clearance but not much else,” a source familiar with military planning told CNN. “It is definitely not designed as a deep penetration warhead.”

Officials also raised concerns that if the MOAB is used against above-ground targets, it could lead to a high number of civilian casualties. 

A source told the outlet that Trump may elect to use the MOAB as he is running out of options and would see the massive bomb as part of psychological warfare. “POTUS has unfortunately put himself in a situation where he is almost compelled to do something and, without the ammunition designed to penetrate that level,” they explained. “You have to look at psychological effects for which the MOAB is well-equipped.”

Trump is the only US president to have authorized the use of a MOAB in combat. In 2017, the US dropped a MOAB on a suspected ISIS tunnel network in Afghanistan.