Satellite images show that the Ukrainians thwarted a Russian attempt towards Kyiv on a pontoon bridge

A senior US official said, on Sunday, that Russia had asked China for military assistance in Ukraine, including drones.

CNN contacted the Russian Embassy in the United States for comment but did not receive an immediate response.

White House National Security Adviser Jake Sullivan told Dana Bash on Sunday that China’s support for Russia is “a concern.”

Sullivan said the United States had made clear to Beijing that there would be “absolute consequences” for “widespread” efforts to give the Kremlin a solution to US sanctions.

“We will not allow that to go ahead and allow Russia to have a lifeline from these economic sanctions from any country anywhere in the world,” he said.

Sullivan is scheduled to meet his Chinese counterpart Yang Jiechi in Rome on Monday.

Chinese embassy spokesman Liu Bingyu told CNN on Sunday that he had not heard of Russia’s request.

“I’ve never heard of that. China is deeply concerned and sad about the situation in Ukraine. We sincerely hope that the situation will calm down and peace will return soon,” Pingyu said. “The current situation in Ukraine is indeed worrying. Maximum efforts should be made to support Russia and Ukraine in moving forward with negotiations despite the difficult situation to reach a peaceful outcome. We support and encourage all efforts leading to a peaceful settlement of the crisis. The top priority now is to prevent an escalation of the crisis. The situation is tense or even out of control. There is consensus on this matter among the international community, including the parties involved.”

The White House said last week that China “complies with the requirements that have been established” on the sanctions.

“Our assessment now is that (China) is sticking to the requirements that have been set out, but we will continue to encourage any country to think a lot about the role they want to play in history as we all look back,” White House Press Secretary Jen Psaki said during a briefing Wednesday.