Russia threatened to escalate attacks into Ukraine after the British government announced it would provide Ukraine with a type of munition that Moscow falsely claims has nuclear components.
The British Ministry of Defense confirmed on Monday that it would supply Ukraine with armor-piercing rounds containing depleted uranium.
Such rounds were developed by the United States during the Cold War to destroy Soviet tanks, including the same T-72 tanks that Ukraine now faces in its quest to break a stalemate in the East.
Depleted uranium is a byproduct of the uranium enrichment process needed to create nuclear weapons. The rounds retain some radioactive properties, but they cannot generate a nuclear reaction like a nuclear weapon would, said RAND nuclear expert and policy researcher Edward Geist.
That did not stop the Russians from warning loudly that the rounds opened the door to further escalation. In the past they have suggested that the war could escalate to the use of nuclear weapons.
Both the British Ministry and the White House dismissed the Russian accusations. But the munition carries risks even if it is not a nuclear weapon.
A look at depleted uranium ammunition:
What is depleted uranium?
Depleted uranium is a byproduct of the process to create the rarer, enriched uranium used in nuclear fuel and weapons. Although much less powerful than enriched uranium and incapable of generating a nuclear reaction, depleted uranium is extremely dense – denser than lead – a quality that makes it very attractive as a projectile.
“It’s so dense and it’s got so much momentum that it just keeps going through the armor — and it heats it up so much that it starts to burn,” Geist said.

When fired, a depleted uranium munition “essentially becomes an exotic metal dart fired at an extraordinarily high velocity,” said RAND senior defense analyst Scott Boston.
In the 1970s, the US Army began making armor-piercing rounds using depleted uranium and has since added it to composite armor armor to strengthen it. It has also added depleted uranium to the munitions fired by the Air Force’s A-10 close-range aircraft, known as the tank killer. The U.S. military is still developing depleted uranium ammunition, specifically the M829A4 armor-piercing round for the M1A2 Abrams main battle tank, Boston said.
In response to a question from The Associated Press, Pentagon spokesman Marine Corps Lt. Col. Garron Garn said in a statement Thursday that “DOD has acquired, stockpiled and used depleted uranium for decades, as these are a long-standing component of some conventional munitions.”
The rounds have “saved the lives of many servicemen in combat,” Garn said, adding that “other countries have long also had depleted uranium, including Russia.”
Garn would not discuss whether the M1A1 tanks being prepared for Ukraine would include depleted uranium armor modifications, citing operational security.

President Vladimir Putin warned on Tuesday that Moscow would “react accordingly, given that the collective West is beginning to use weapons with a ‘nuclear component.’
The British “have lost their bearings,” Russian Foreign Minister Sergey Lavrov said, warning that the munitions are “a step toward accelerating escalation.”
Defense Minister Sergei Shoigu said the announcement was “another step, and there aren’t that many of them left.”
The White House condemned Russia’s claims as disinformation.
“Make no mistake, this is yet another straw man through which the Russians are pushing an effort,” said John Kirby, a spokesman for the US National Security Council.
Russia also has depleted uranium munitions and simply does not want Ukraine to have them either, according to a White House official, who was not authorized to comment on the matter and spoke on condition of anonymity.
Pentagon Press Secretary Air Force Brig. Gen. Pat Ryder said Monday that the United States, to his knowledge, did not send depleted uranium munitions from its own arsenal to Ukraine.
Not a bomb, but still a risk
Although depleted uranium munitions are not considered nuclear weapons, their release of low levels of radiation has prompted the UN nuclear watchdog to urge caution in handling and warn of the possible dangers of exposure.
The handling of such munitions “should be kept to a minimum and protective clothing (gloves) should be worn,” the International Atomic Energy Agency warns, adding that “a public information campaign may therefore be required to ensure that people avoid handling projectiles.”
“This should be part of any risk assessment and such precautions should depend on the scale and number of munitions used in an area.”

The IAEA notes that depleted uranium is primarily a toxic chemical, as opposed to a radiation hazard. Particles in aerosols can be inhaled or ingested, and while most would be re-excreted, some could enter the bloodstream and cause kidney damage.
“High concentrations in the kidneys can cause damage and in extreme cases kidney failure,” says the IAEA.
The low-level radioactivity in a round of depleted uranium “is a bug, not a feature” of the munition, Geist said, and if the U.S. military could find another material with the same density but without the radioactivity, it would likely use it instead.
Depleted uranium munitions were used in the 1991 Gulf War against Iraq’s T-72 tanks and again in the 2003 invasion of the country, as well as in Serbia and Kosovo. American military veterans of those conflicts have questioned whether their use led to the illnesses they now face.
Vyacheslav Volodin, the speaker of the lower house of the Russian parliament, said that shipments of rounds containing depleted uranium could lead to “a tragedy on a global level that will primarily affect European countries.”
Volodin said that the use of such American munitions in the former Yugoslavia and Iraq led to “radioactive contamination and a sharp increase in oncological diseases.”
Associated Press writers Aamer Madhani in Washington, Frank Jordans in Berlin and Menelaos Hadjicostis in Nicosia, Cyprus contributed to this report.