Jake Sullivan speaks at a press briefing at the White House in Washington
U.S. national security adviser Jake Sullivan speaks to reporters during a press briefing at the White House in Washington, U.S., July 11, 2022. Reuters

White House national security adviser Jake Sullivan has been engaged in confidential talks with senior Russian officials aimed at lowering the risk of a broader war over Ukraine, a source familiar with the conversations said on Monday.

The source, who asked to remain unidentified, said the talks are ongoing. The Sullivan talks were first reported by the Wall Street Journal.

Sullivan said in September that the United States had communicated publicly and privately with the Russians about Russian President Vladimir Putin's threats to use nuclear weapons in the Ukraine war.

While Sullivan had said publicly that there would be tragic consequences should Russia resort to nuclear weapons, it was unclear how this message was being communicated privately. The source said the talks had been taking place in recent months.

Sullivan, speaking at an event at the Economic Club of New York, did not say he had been engaged himself in direct talks but noted he had said repeatedly that "we have channels to communicate with the Russian Federation at senior levels."

"We have done so when it's been necessary to clarify potential misunderstandings and try to reduce risk and reduce the possibility of catastrophe like the potential use of nuclear weapons," he said.

The White House, which has been careful not to make diplomatic moves about Ukraine without Ukrainian involvement, did not deny the talks.

"We reserve the right to speak directly at senior levels about issues of concern to the United States. That has happened over the course of the past few months. Our conversations have focused only on ... risk reduction and the U.S.-Russia relationship," White House spokesperson Karine Jean-Pierre told reporters.

She said U.S. support for Ukraine will be "unflinching and unwavering."