Russian President Vladimir Putin on Tuesday condemned British plans to send tank ammunition that contains depleted uranium to Ukraine, saying Moscow would be forced to respond accordingly.
Speaking in London on Monday, Minister of State for Defence Annabel Goldie said some of the ammunition for the Challenger 2 battle tanks that Britain is sending to Ukraine includes armour piercing rounds which contain depleted uranium.
"If all this happens, Russian will have to respond accordingly, given that the West collectively is already beginning to use weapons with a nuclear component," Putin said in remarks after a summit with Chinese President Xi Jinping. He did not elaborate.
Russian politicians and commentators have made a series of combative remarks since the invasion of Ukraine last year, suggesting Moscow would - if necessary - be prepared to deploy its vast nuclear arsenal.
Defence Minister Sergei Shoigu said the British decision left fewer and fewer steps before a potential "nuclear collision" between Russia and the West.
"Another step has been taken, and there are fewer and fewer left," he told reporters in remarks cited by domestic agencies.
Depleted uranium is used in weapons because it can penetrate tanks and armour more easily due to its density and other physical properties, a point that Goldie made.
It is a particular health risk around impact sites, where dust can get into people's lungs and vital organs.
"Naturally, Russia has something to answer this with," Shoigu told reporters when asked about the ammunition.
Earlier, Russian Foreign Ministry spokeswoman Maria Zakharova called the plan the "Yugoslavia scenario", saying the ammunition caused cancer and infected the environment.