There was a real risk of Russia using tactical nuclear weapons in the early months of the war in Ukraine, CIA chief Bill Burns revealed at the FT Weekend festival in London.

Burns said the surprise incursion into northeastern Ukraine at the time fueled fears that Putin might use more extreme measures.

"In the fall of 2022, there was a real risk of possible use of tactical nuclear weapons," Burns said, according to the Telegraph.

"The president sent me to talk to my Russian counterpart to make it clear what the consequences of this kind of escalation would be. We continued to be very direct in those conversations. We could not allow ourselves to be intimidated by such a rattle of arms or threats. But we had to be aware of the possibility of something like this happening," Burns explained.

In November 2022, Burns met with his Russian counterpart in Ankara. The White House also reported on the meeting at the time: "Burns will convey a message about the consequences of a possible Russian use of nuclear weapons and the risks of escalation to strategic stability."

The Telegraph recalls that in October 2022, fears of a possible Russian attack were raised after Defense Minister Sergei Shoigu said that Ukraine was planning to use a radioactive bomb.

The UK immediately rejected the claims, while Ukrainian President Volodymyr Zelensky said it was clear Russia was planning a dirty bomb attack of its own.

Richard Moore, the head of British intelligence (MI6), said: “All the time there is only one side talking about nuclear escalation, and that is Putin. This is deeply irresponsible and no one in the West will be intimidated by such threats or any other behavior by the Russian state. Putin is a bully. He will continue to wave the gun from time to time, but he seems desperate.”