CIA Director Bill Burns traveled to Kyiv to meet with Ukrainian President Volodymyr Zelensky and his intelligence counterparts on Tuesday, a US official said.   

  Burns, the official said, was safely inside the U.S. Embassy during Russian missile launches across the country, including explosions that rocked the nation’s capital.   

  The CIA director’s trip to Kyiv follows Monday’s meeting in Ankara, Turkey, with his Russian counterpart, Sergey Naryshkin – and is the second known visit to Kyiv in less than a month.   

  While there, Burns said, he “discussed the U.S. warning to Russia’s SVR chief not to use nuclear weapons and reinforced the U.S. commitment to support Ukraine in its fight against Russian aggression.”   

  The flurry of back-channel communications comes less than a week after Russia announced its withdrawal from a key Ukrainian city and has sparked a quiet debate in Washington over whether or not to encourage Ukraine to seek a diplomatic resolution to the war.  It also comes as the US grows concerned that Russia could turn to a nuclear weapon in its struggling offensive.   

  Burns and other US officials have said publicly that they see no evidence that Moscow is actively preparing to take such a step, but officials with knowledge of the intelligence services warn that the risk is perhaps the highest since Russia invaded Ukraine in February.   

  President Joe Biden has leaned heavily on Burns, a seasoned diplomat with deep experience in Russia, as a quiet messenger in the ongoing conflict.   

  Burns was sent to Ankara on Monday to “communicate with Russia about risk management, particularly nuclear and risks to strategic stability,” a national security spokesman said.  The spokesman emphasized that he was not conducting any kind of negotiations.   

  In Kyiv in October, he “reinforced the U.S. commitment to provide support to Ukraine in its fight against Russian aggression, including continued intelligence sharing,” a U.S. official told CNN at the time.   

  Burns was sent to Moscow last November, before Russia invaded Ukraine, to warn the Kremlin about the consequences of an invasion.  He has also engaged in discussions with Naryshkin about American citizens detained in Russia, including Brittney Griner and Paul Whelan.