The official, who wasn’t authorized to speak publicly, would not offer specifics about Russia’s request or how the United States came to learn about it. The White House wouldn’t comment on the record.

Since Russia invaded Ukraine on February 24, Russian President Vladimir Putin’s forces have seen their campaign to take the capital, Kyiv, and other regions mostly stalled because of Ukraine’s Western-backed resistance. The introduction of thousands of anti-tank and anti-aircraft missiles, along with other advanced equipment, has helped overmatched Ukrainian troops destroy Russia’s warplanes, helicopters and other vehicles. While Russia maintains a military advantage, experts say, the hardware losses have made an already complicated campaign that much harder.

The revelation of the Kremlin’s request comes a day before National Security Adviser Jake Sullivan is set to meet Yang Jiechi, China’s top foreign policy official, in Rome to discuss the Russia-Ukraine war.

Earlier on Sunday, Sullivan told CNN’s “State of the Union” that “we are communicating directly, privately to Beijing that there will absolutely be consequences for large-scale sanctions evasion efforts or support to Russia to backfill them. We will not allow that to go forward and allow there to be a lifeline to Russia from these economic sanctions from any country anywhere in the world”.

The US and Europe-led economic sanctions campaign to punish Russia for the invasion has pushed Moscow to seek more economic help from China.

“We have part of our gold and foreign exchange reserves in the Chinese currency, in yuan,” Russian Finance Minister Anton Siluanov said during a Sunday TV interview, adding, “And we see what pressure is being exerted by Western countries on China in order to limit mutual trade with China.”

The military support Russia needs from China is less clear. Perhaps Moscow is asking for “exploratory talks”, said Michael Kofman, Russia director at the Virginia-based CNA think tank, or it “could be chips, which is what they really need”. But the majority of semiconductors, he noted, come from Taiwan, whose government is enforcing the global export restrictions on Russia.

Russia has “definitely set themselves behind several years of procurement in terms of equipment”, Kofman said.

The Kremlin’s request raises important questions about how Russia sees its progress, or lack thereof, on the Ukrainian battlefield and about the Moscow-Beijing relationship writ large.

Seeking military assistance just two weeks into the war could indicate Russian military leaders assess that they need a backfill of equipment to sustain the invasion, especially as the campaign to take Kyiv remains mostly stalled.

And how Chinese leader Xi Jinping chooses to back Putin — with whom he has met 38 times — could provide a clear signal about the strength of their ties. Usually Russia sells weapons to China, so agreeing to the request would underscore a changed dynamic.

Later, a spokesperson for the Chinese embassy to the United States rejected media allegations that Moscow had approached Beijing for military equipment and other logistical support, Reuters reported on Sunday.

Liu Pengyu, a spokesman for the embassy, reportedly told the news agency that he had "never heard of that". 

China's aim, according to Liu, is to keep the Kremlin's special military operation in Ukraine from spiraling out of control.

"The current situation in Ukraine is indeed disconcerting," the Chinese diplomat noted in response to Reuters.

"The high priority now is to prevent the tense situation from escalating or even getting out of control," Liu added.