When loaded with depleted-uranium bullets, the A-10s fired what is called a “combat-mix,” meaning the aircraft’s cannon fires five depleted-uranium rounds to one high explosive incendiary bullet.
The strikes, which involved 30mm cannon fire, rockets and guided bombs, destroyed more than 300 vehicles, mostly civilian tanker trucks, the Pentagon said at the time. The two incidents were championed by the Pentagon, and footage of trucks being destroyed was posted online. The Pentagon said that no civilians were present during the bombardment because fliers had been dropped before strafing runs warning those in their trucks to flee.
Before the November strikes, the Pentagon said it would not use depleted-uranium munitions in the campaign against the Islamic State. In response to a query from a reporter in February 2015, Capt. John Moore, a spokesman for the U.S.-led anti-ISIS coalition in Iraq and Syria said in an email that “U.S. and Coalition aircraft have not been and will not be using depleted uranium munitions in Iraq or Syria during Operation Inherent Resolve.”
Later that year, the Pentagon’s stance toward depleted uranium changed. As U.S.-led forces ramped up their campaign to go after the Islamic State’s cash flow, U.S. planners for Operation Tidal Wave II decided that depleted-uranium ammunition would be the most effective weapon for targeting hundreds of Islamic State oil trucks in the Syrian desert. Jacques said that U.S. forces wanted to ensure that trucks would be rendered completely inoperable, adding that depleted-uranium rounds were the best way to achieve that, rather than the A-10’s standard high explosive cannon rounds. Typically, depleted-uranium rounds are used on armored vehicles, such as tanks and troop transports, and there is no international treaty or rule that explicitly bans their use.
“Given the international opprobrium associated with the use of depleted uranium, we had been pretty astonished to hear that it had been used in operations in Syria,” said Doug Weir, the International Coordinator for the Coalition to Ban Uranium Weapons. “The U.S. consistently states that the weapons are for anti-armor use, although their record from Iraq … was further evidence that this doesn’t really bear close scrutiny.”
Depleted uranium is the byproduct of the enriched uranium needed to power nuclear reactors. Depleted uranium is roughly 0.7 times as radioactive as natural uranium, and its high density makes it ideal for armor-piecing rounds such as the PGU-14 and certain tank shells. Depleted uranium is also used to reinforce certain types of armor and has a number of nonmilitary uses, such as ballast in ships.
Whether exposure to depleted uranium causes adverse health effects has been debated. When it was used during the 1999 NATO bombing campaign in Kosovo, the United Nations advised that children stay away from the impact zones. The Iraqi government has also routinely stressed the danger the munitions pose to its people, soil and air. Depleted-uranium rounds were used in the hundreds of thousands of attacks during the 1991 Persian Gulf War and again in the opening salvos of the 2003 invasion of Iraq.
In a 2014 United Nations report on depleted-uranium munitions, the International Atomic Energy Agency said that “the existence of depleted-uranium residues dispersed in the environment, when observed as confined contamination of soils, vegetables, water and surfaces, does not pose a radiological hazard to the local populations.” The agency did say, however, that direct contact with larger amounts of depleted uranium through the handling of scrap metal, for instance, could “result in exposures of radiological significance.”
Jacques did not rule out the possibility that the U.S.-led coalition might use depleted-uranium rounds again, adding that the locations where they were used in November 2015 have been marked for cleanup in the future. Sanitizing the areas where the ammunition was fired might prove difficult, however, as the area is still primarily controlled by the Islamic State, and whatever scrap was left behind from the strikes has likely been recovered and sold.