On Monday, CIA Director William Burns met in Ankara with the head of Russia's Foreign Intelligence Service, Sergei Naryshkin.

U.S. and Russian intelligence chiefs have met face-to-face to discuss the dangers of Moscow's nuclear threats against Ukraine, as well as the fateof U.S. prisoners who Washington says are being held unfairly by Russia.

The Kremlin said that the talks were the initiative of the American side.

The White House said Burns, who was the U.S. ambassador to Russia from 2005 to 2008 and speaks Russian, did not negotiate an end to the war.

His message to Naryshkin concerned the consequences in the event of Russia's use of nuclear weapons and the risk of "escalation of strategic instability," the White House said in a statement.

In recent months, the U.S. has repeatedly warned Moscow against using tactical nuclear weapons in Ukraine after the Kremlin's transparent hints that Russia could take such a step.

In September, Vladimir Putin accused the West of wanting to destroy Russia, stressing that it would use "all available means" to protect its territory.

This was perceived as a veiled threat to use nuclear weapons, and the U.S. said it would take it seriously.

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Burns' meeting with Naryshkin was confirmed by a spokesman for Turkish President Erdogan, who has become an important mediator between Russia and Western countries.

The White House statement stressed that Mr. Burns did not conduct any negotiations on the settlement of the conflict and that Washington will firmly adhere to the fundamental principle of "nothing about Ukraine without Ukraine."

The exact content of the conversation in Ankara is unknown — a CIA spokesman said they never discuss such missions. But the meeting took place at a crucial moment - after the fall of Kherson, when many are waiting for how Moscow will react to this failure.

While Naryshkin is not believed to have the same weight in Moscow as Burns in Washington, the U.S. capital hopes the face-to-face meeting will give the CIA director some idea of what Moscow is thinking.