U.S. Arms Warplanes With ‘Bunker Busting’ Bombs in Message to Iran

The Air Force’s A-10 Warthogs are carrying 250-pound precision-guided weapons in the Mideast

By Dion Nissenbaum

The U.S. military is for the first time putting 250-pound “bunker busting” bombs on attack aircraft recently sent to the Middle East, American officials said, in the latest move to deter Iran.

The decision to put more powerful weapons on a squadron of A-10 Warthogs was designed to give pilots a greater chance of success in destroying ammunition bunkers and other entrenched targets in Iraq and Syria, where U.S. forces have been repeatedly targeted by Iran-backed fighters, the officials said.

The move marks the first time that the U.S. military will put these precision-guided weapons on board the Warthogs, which were recently refitted so that they could each carry up to 16 bunker busters, known formally as GBU-39/B bombs.

“The A-10s are highly effective at some of the things we need to do,” said Air Force Lt. Gen. Alexus Grynkewich, who oversees U.S. military operations in the skies above Syria and 20 other nations in the Middle East and Southeast Asia as head of the U.S. Air Forces Central Command.

The U.S. military recently installed special racks on the Warthogs. PHOTO: U.S. AIR FORCE

The powerful bombs are arriving in the Middle East at a time of heightened tensions with Iran. On Thursday, Iran’s Islamic Revolutionary Guard Corps detained an oil tanker in the Gulf of Oman as it carried crude to the U.S. from Kuwait. 

The vessel, a Marshall Islands-flagged ship called the Advantage Sweet, remained in detention on Friday and could be held for a long time. 

Iran says the Advantage Sweet collided with an Iranian ship in the Persian Gulf, causing injuries, and then tried to escape. The U.S. Navy says Iran violated international law by detaining the ship and called for its immediate release.

The Pentagon sent the Warthog squadron—usually around 12 planes—to the Middle East last month after Iran-backed forces carried out a series of attacks on U.S. bases in Syria, including one suicide-drone strike that killed an American contractor. President Biden responded to the attacks by ordering airstrikes on Iran-backed militants in Syria. 

The new squadron represents a 50% increase in the number of attack aircraft in the region, Gen. Grynkewich said. 

An A-10 pilot at Nellis Air Force Base. PHOTO: U.S. AIR FORCE

Moving the Warthogs into the Middle East was part of a broader effort to beef up the American military presence amid rising concerns about attacks by Iran and its militant allies across the region.

The U.S. military also announced the arrival last month of a guided-missile submarine in the Middle East, a public show of force. At the time, U.S. officials said they had intelligence that Iran was preparing to carry out a drone attack on a commercial ship in the region, something Washington has accused Tehran of doing several times in recent years. 

Concerns about that threat eased after the USS Florida, which can carry 150 Tomahawk missiles, arrived in the Red Sea, the officials said.

The Iranian Foreign Ministry didn’t respond to a request for comment. Earlier this month, after the deployment of the USS Florida, the Foreign Ministry’s spokesman Nasser Kanaani said the U.S. was trying to “cover up the decline of its power in the world.”

“The American regime has moved in a direction contrary to the will of the nations of the region,” he said on Twitter.

The Pentagon has about 900 military personnel working on small bases in Syria, where they focus primarily on preventing Islamic State militants from regaining a foothold in the region where its fighters built a self-proclaimed caliphate before it was toppled by U.S.-backed forces in 2019.

American troops in Syria and Iraq have been repeatedly targeted by Iran-backed forces using rockets and drones. The most recent rocket attack targeting U.S. forces in Syria took place in early April.

Mr. Biden has ordered a handful of airstrikes targeting militants in Syria since he took office in 2021.

In an effort to expand those abilities, the U.S. military recently installed special racks on the Warthogs, giving them a new ability to carry precision-guided bombs. 

The upgrade will give the Warthogs more firepower than F-15 jet fighters, U.S. officials said. It also represents an advance on the military’s efforts to demonstrate the value of the aging Warthog fleet that Pentagon officials have been trying to retire for more than a decade.

The relatively slow-flying plane is best used to provide close air support for U.S. forces in places like Syria where militants have no planes to challenge American pilots in the skies. But the Warthog is seen as a poor fit in Asia, where it is vulnerable to China’s air defenses.

—Aresu Eqbali contributed to this article.

Write to Dion Nissenbaum at dion.nissenbaum@wsj.com