The United Kingdom recently announced that it would send a squadron of Challenger II main battle tanks to Ukraine and confirmed that those tanks would be armed with armor-piercing depleted uranium rounds.

Russian President Vladimir Putin reacted to the news by warning that his nation would "respond accordingly" if the U.K. and the collective West proceeded with introducing "nuclear component" weaponry into Ukraine's arsenal, the Daily Mail reported.

Depleted uranium is a byproduct of the nuclear enrichment process that is substantially less radioactive than normal uranium and, due to its incredible density and weight, is used by the militaries of several nations to create armor-piercing ammunition for tanks and aircraft.

U.K. confirms provision of depleted uranium tank rounds to Ukraine

On Monday, a member of the U.K. parliament formally asked the U.K. government whether any of the ammunition being provided to Ukraine for its defense against the ongoing Russian invasion contained depleted uranium.

In a written response, Annabel Goldie, a U.K. Defense minister, replied, "Alongside our granting of a squadron of Challenger 2 main battle tanks to Ukraine, we will be providing ammunition including armor-piercing rounds which contain depleted uranium.

"Such rounds are highly effective in defeating modern tanks and armored vehicles," Goldie added.

"Russia will have to respond accordingly"

One day later, as Russian President Putin spoke with reporters during a bilateral meeting in Moscow with Chinese President Xi Jinping, a mention was made of that announcement from the U.K. Defense Ministry in the Russian leader's remarks.

While discussing the "developments around Ukraine" and a peace proposal put forward by China, Putin said, "The U.K. deputy defense minister announced that the United Kingdom would supply not only tanks to Ukraine, but also depleted uranium shells."

"It seems that the West really has decided to fight Russia to the last Ukrainian -- no longer in words, but in deeds," he continued. "But in this regard, I would like to note that if all this comes to pass, then Russia will have to respond accordingly."

"What I mean is that the collective West is already starting to use weapons with a nuclear component," Putin added.

"Fewer and fewer" steps remain before "nuclear collision," Russian minister warns

The Daily Mail reported that Russian President Putin was echoed by Russian Defense Minister Sergei Shoigu, who told reporters that in terms of a potential nuclear disaster, "Another step has been taken, and there are fewer and fewer left."

Asked to clarify if he was referencing the possibility of a "nuclear collision," Russia's top general reiterated, "'It was not by chance that I told you about steps. There are fewer and fewer," and further asserted that if depleted uranium rounds were actually provided to and used by Ukraine, then "Russia has something to answer this with."

A spokesperson for the Russian Foreign Ministry also made mention of the "Yugoslavia scenario" in relation to the ammunition that was in reference to its use by U.S. and allied forces in the Balkans in the 1990s and allegations that the depleted uranium rounds led to increased rates of cancer and caused environmental damage.

U.K. defends its decision

In response to Russian President Putin's remarks, the BBC reported that the U.K. Defense Ministry defended its decision to provide Ukraine with depleted uranium rounds as they are "a standard component and has nothing to do with nuclear weapons."