Russian President Vladimir Putin said Tuesday that Moscow would "respond accordingly" if Britain gives Ukraine military supplies, including armor-piercing ammunition containing depleted uranium.

"[The U.K.] announced not only the supply of tanks to Ukraine, but also shells with depleted uranium," Putin told reporters after talks at the Kremlin with his Chinese counterpart Xi Jinping. "I would like to note that if all this happens, then Russia will have to respond accordingly ... The collective West is already starting to use weapons with a nuclear component."

Putin was reacting to a written response by a U.K. defense minister, Annabel Goldie, who was asked whether "any of the ammunition currently being supplied to Ukraine contains depleted uranium."

She responded on Monday that "alongside our granting of a squadron of Challenger 2 main battle tanks to Ukraine, we will be providing ammunition including armour piercing rounds which contain depleted uranium." She said the rounds "are highly effective in defeating modern tanks and armoured vehicles."

Depleted uranium is a by-product of the nuclear enrichment process used to make nuclear fuel or nuclear weapons. It is around 60% as radioactive as natural uranium and its heaviness lends itself for use in armor-piercing rounds, since it helps them easily penetrate steel. 

Hamish de Bretton-Gordon, a chemical weapons expert and former British Army officer, said Putin's comments accusing the West of supplying Ukraine with "weapons with a nuclear component" were "absolutely bonkers" and "completely wrong," noting that depleted uranium "cannot be used as a nuclear fuel or turned into a nuclear weapon." He said Putin is trying "to persuade Xi to give him weapons and to terrify people in the West that he is planning to escalate to nuclear weapons."

"Putin has been using the nuclear escalation card since the beginning of the war to keep NATO out but it has not worked," de Bretton-Gordon told CBS News. "As his army is disintegrating, he is trying to persuade China to give him weapons and thinks threatening nuclear weapons will make NATO force [Ukrainian President Volodymyr Zelenskyy] to the negotiating table."

The United Nations Environment Program has described depleted uranium as a "chemically and radiologically toxic heavy metal." Depleted uranium munitions were used in conflicts in the former Yugoslavia and Iraq, and were suspected of being a possible cause of "Gulf War syndrome," a collection of debilitating symptoms suffered by veterans of the 1990-91 war. 

Researchers from the U.K.'s University of Portsmouth tested sufferers to examine levels of residual depleted uranium in their bodies and say their 2021 study "conclusively" proved that none of them were exposed to significant amounts of depleted uranium.

 Anti-nuclear organization CND condemned the decision to send the ammunition to Ukraine, calling it an "additional environmental and health disaster for those living through the conflict" as toxic or radioactive dust can be released on impact.

"CND has repeatedly called for the U.K. government to place an immediate moratorium on the use of depleted uranium weapons and to fund long-term studies into their health and environmental impacts," said CND general secretary Kate Hudson.