National Security Advisor Jake Sullivan has held undisclosed talks with top Russian officials in hopes of reducing the risk the war in Ukraine spills over or escalates into a nuclear conflict, the Wall Street Journal reported on Sunday.
The newspaper cited US and allied officials as saying that Sullivan, President Joe Biden's top aide on national security, held confidential conversations in recent months with Kremlin aide Yuri Ushakov and Russian Security Council secretary Nikolai Patrushev, Sullivan's counterpart, that were not disclosed publicly.
The White House declined to comment on the report, responding to questions about the story only with a statement attributed to National Security Council spokesperson Adrienne Watson: "People claim a lot of things."
The Wall Street Journal said the officials did not provide the dates or the number of calls.
Few high-level contacts between US and Russian officials have been made public in recent months as Washington has insisted that any talks on ending the war in Ukraine be held between Moscow and Kyiv.
The reported conversations took place as the West has accused Moscow of ramping up nuclear rhetoric, most recently by repeatedly accusing Kyiv of planning to use a radioactive "dirty bomb," without offering evidence.
Kyiv has denied having such a plan and the United States and other Western nations have said Russia could be planning to orchestrate such an attack itself and use it as a pretext to escalate the conflict.
Russia in turn has accused the West of "encouraging provocations."
Sullivan traveled to Kyiv on Friday and pledged Washington's "unwavering and unflinching" support for Ukraine.