What are depleted uranium shells? The controversial armour-piercing munitions being used in Ukraine

When fired, depleted uranium becomes ‘essentially an exotic metal dart fired at extraordinarily high speed’

The depleted uranium anti-tank rounds soon to be in Ukraine’s military stockpiles have kicked up a debate over its use in the continuing Russian invasion.

Announced by the Pentagon in the latest military tranche on Wednesday, the controversial rounds have spread alarm among Vladimir Putin’s ministers who have warned against the escalation yet again.

Britain has already promised armour-piercing rounds containing depleted uranium to Ukraine in March. Prime minister Rishi Sunak had backed drawing out the rounds from the UK military’s stockpiles ultimately “to degrade and deter – primarily – Russian aggression”.

But what are these depleted uranium munitions?

The 120mm anti-tank shells made of depleted uranium are self-sharpening and flammable penetrator in munitions. They are made of naturally occurring Uranium which has been stripped of mostly – not all – of its radioactive matter.

So while it is not a nuclear weapon in itself, it acts as a fuel and also as a great explosive that can be used in tank armour, pressed between sheets of steel armour plate.

They can be paired with top-tier tanks Western nations have already provided to Ukraine, and are particularly expected to boost the performance of 31 M1A1 Abram tanks set to be sent to the war-hit nation this fall.

These rounds first emerged in the 1970s when the US army started making the armour-piercing rounds and has since used it along with tank armour to multiply the firing effect.

Incredibly dense, more than lead, depleted uranium is considered a top-tier choice for projectiles.

When fired, it becomes “essentially an exotic metal dart fired at an extraordinarily high speed”, RAND senior defence analyst Scott Boston said.

“It’s so dense and it’s got so much momentum that it just keeps going through the armour – and it heats it up so much that it catches on fire,” Edward Geist, a nuclear expert at research organisation RAND said.

The depleted uranium has also been added to the US ammunition fired by the Air Force’s A-10 close air support attack plane, known as the tank killer.

Depleted uranium munitions, as well as depleted uranium-enhanced armour, have been previously used by US tanks in the 1991 Gulf War against Iraq’s T-72 tanks and again in the invasion of Iraq in 2003, as well as in Serbia and in Kosovo.

Is the risk alarming?

The UN nuclear watchdog has warned of the emissions of low levels of radiation from depleted uranium when handling and also warned of possible dangers of explosion. This is a bug, not a feature of the munition, says Mr Geist.

Categorically, depleted uranium is not marked as a nuclear weapon.

It is mainly a toxic chemical, as opposed to a radiation hazard. Particles in aerosols can be inhaled or ingested, and while most would be excreted again, some can enter the bloodstream and cause kidney damage.

“High concentrations in the kidney can cause damage and, in extreme cases, renal failure,” the International Atomic Energy Agency has said.

The US troops have questioned whether some of the ailments they now face were caused by inhaling or being exposed to fragments after a munition was fired or their tanks were struck, damaging uranium-enhanced armour.

Experts have said that if the US military could find another material with the same density but without the radioactivity, it would likely switch.

The IAEA has warned that handling of depleted uranium “should be kept to a minimum and protective apparel (gloves) should be worn” and “a public information campaign may, therefore, be required to ensure that people avoid handling the projectiles”.

Initial signs of radioactivity from the Ukraine war have started trickling in. Russian foreign ministry spokesperson Maria Zakharova had recently claimed that the use of these munitions has already led to radioactive contamination.

How has Russia reacted?

In March, Russia was fuming after the Rishi Sunak administration announced it will give depleted uranium rounds to Ukraine, prompting them to issue nuclear threats.

This time, after the US joined Britain in sending the depleted uranium shells, Moscow snapped and called the latest military aid of depleted uranium a “criminal act” beyond just escalation.

“It is a reflection of Washington’s outrageous disregard for the environmental consequences of using this kind of ammunition in a combat zone. This is, in fact, a criminal act, I cannot give any other assessment,” Russian deputy foreign minister Sergei Ryabkov said.

He also reiterated previous warnings by Russia about the risk of a nuclear war, because of what he called Western “pressure” on Moscow.

“Now this pressure is dangerously balancing on the brink of direct armed conflict between nuclear powers,” he said.

In March, Vladimir Putin had warned that Moscow would "respond accordingly, given that the collective West is starting to use weapons with a ‘nuclear component.’”

Several days later, Putin said Russia’s response will see Moscow stationing tactical nuclear weapons in neighbouring Belarus, action to which effect was announced in July as Putin and the Belarusian president said they had already shipped some of the weapons.