Fact Check: "Massive Ordnance Penetrator is the largest bomb ever used by the U.S."
What We Know
The claim that the Massive Ordnance Penetrator (MOP) is the largest bomb ever used by the U.S. is misleading. The MOP, officially designated as the GBU-57A/B, is a 30,000-pound (approximately 14,000 kg) precision-guided munition designed for penetrating deeply buried targets, such as bunkers. It is 20.5 feet (6.2 meters) long and is specifically designed to be carried by the Northrop B-2 Spirit bomber, making it a significant advancement in U.S. military capabilities (Wikipedia).
However, while the MOP is indeed the heaviest conventional bomb in the U.S. arsenal, it is not the largest bomb ever used. The GBU-43/B Massive Ordnance Air Blast (MOAB), also known as the "Mother of All Bombs," weighs approximately 22,000 pounds (about 9,800 kg) and is designed to create a massive blast over a wide area rather than penetrate deeply underground. The MOAB was famously used in Afghanistan in 2017 against ISIS targets (Washington Post).
Analysis
The claim's validity hinges on the definitions of "largest" and "heaviest." The MOP is the heaviest bomb designed for specific tactical applications, particularly against fortified underground targets. However, the MOAB, which is lighter than the MOP, is designed for a different purpose and is often cited as the largest bomb due to its explosive yield and area of effect (NPR).
The sources used to evaluate this claim are credible. The Wikipedia entry provides a detailed overview of the MOP's specifications and operational history, while the Washington Post and NPR articles offer insights into the bomb's use in combat and its intended purpose. The distinction between the MOP and MOAB is critical, as it highlights the differences in design and application of these munitions.
Moreover, the MOP's first combat use was reported in June 2025 during strikes on Iranian nuclear facilities, which adds context to its operational deployment (Wikipedia, Washington Post).
Conclusion
Verdict: False. The claim that the Massive Ordnance Penetrator is the largest bomb ever used by the U.S. is inaccurate. While it is the heaviest conventional bomb in the U.S. arsenal, it is not the largest when considering other factors such as explosive yield and area of effect, particularly in comparison to the MOAB.
