A Massive Ordnance Air Blast, or MOAB, nicknamed the "Mother of All Bombs" because of its acronym. DoD Photo Editor's note: An earlier version of this story cited a figure from a 2011 newspaper article on the Massive Ordnance Air Blast bomb. An Air Force representative provided an official, updated estimate on Friday.

Some of President Donald Trump's critics were quick to decry the cost of dropping the "mother of all bombs" on an ISIS target in Afghanistan on Thursday.

But the number heavily cited across social media, $314 million, was never confirmed by the US military, which has developed 20 such bombs, officially called the Massive Ordnance Air Blast.

The US Air Force dropped one MOAB — the largest nonnuclear bomb in the US's arsenal — on an ISIS target in a remote part of far northeast Afghanistan, according to the Pentagon. The White House press secretary, Sean Spicer, said the goal was to destroy "a system of tunnels and caves that ISIS fighters used to move around freely, making it easier for them to target US military advisers and Afghan forces in the area."

One MOAB costs about $170,000, an Air Force representative said Friday. The Air Force has not confirmed the development costs associated with the larger weapons system.

Many celebrities and other Trump critics used Twitter to express frustration at the administration's authorization of using such an expensive bomb, but they cited an unverified cost believed to have been associated with the entire development program:

For comparison, aircraft from the USS Harry S. Truman dropped 1,118 smaller bombs in Iraq and Syria from late December 2015 to mid-April 2016 as part of the US-led Operation Inherent Resolve. A general-purpose 1,000-pound MK-83 costs about $12,000.

Alex Lockie contributed to this post.