Senior US government officials say China has not provided Russia with any lethal aid so far, and that the United States is monitoring the situation closely.

On Sunday, White House National Security Advisor Jake Sullivan said on ABC television that the US government has not seen Beijing "take the step of providing weapons" to Moscow "at this point."

Sullivan added, "We know they haven't taken it off the table."

CIA Director William Burns said in an interview with CBS television on Friday that the US is "confident that the Chinese leadership is considering the provision of lethal equipment."

Burns said, "We also don't see that a final decision has been made yet, and we don't see evidence of actual shipments of lethal equipment."

Some Western media outlets say Beijing is considering providing unmanned aircraft and ammunition to Russia.