The officials did not say what specific evidence they had to support the intelligence, which was originally reported by The Wall Street Journal and confirmed to NBC News by a former U.S. official and a Western official briefed on the matter.
China's Ministry of Foreign Affairs did not respond to a request for comment about the disclosure, which came after Beijing put forward a 12-point peace plan on Friday — on the one-year anniversary of Russia's invasion of Ukraine.
It called for both countries to agree to a gradual de-escalation, to keep nuclear facilities safe and to establish humanitarian corridors, and to prevent attacks on civilian populations.
Earlier this month Beijing hit back strongly against U.S. allegations that it may be providing nonlethal military assistance to Moscow, telling Washington to stay out of its relationship with the Kremlin.
It “could be a significant development” if China did decide to provide arms to Russia, Rob Lee, a senior fellow at the Foreign Policy Research Institute, a Philadelphia-based think tank, said on Twitter.
He added that “artillery ammunition availability for Ukraine and Russia is arguably the single most important variable that could influence the course of the war.”
But Keir Giles, a Russia expert and a senior consulting fellow at Chatham House, a London based think tank, said by telephone Sunday that “previous assessments and predictions of Russia imminently running out of a given type of ammunitions has not turned out to be the case in real life.”
He also said that if Moscow was turning to alternative suppliers “over and above the drones it has received from Iran,” then it was “an indication that they are depleting their post-Cold War stocks of arms and munitions at a pace they feel is unsustainable.”
From a Chinese perspective it is important that Russia is not defeated, according to Michael A. Horowitz, a geopolitical and security analyst, and head of intelligence at Le Beck consultancy.
Beijing, he said, had “already been providing Russia with significant support, be it in the form of increased oil imports, dual-use components, micro-chips imported from Western countries and satellite imagery.”
He added that if China provided only arms munitions to Russia, that might not register in Europe, which along with the U.S. is one of its main trading partners. “But if they provide anything beyond that, including artillery shells that are heavily used in Ukraine, or drones, then Europe will feel pressured to respond,” he said.
“China would not necessarily be unhappy with a diminished Russia that would increasingly have to align with Beijing. But avoiding a Russian defeat is in Beijing’s interest,” he said.
The goal was “to make sure Russia can’t lose, and to force a negotiated settlement,” he said, saying that this was why China released the peace plan.
After China unveiled those proposals, Ukraine's president, Volodymyr Zelenskyy, said Friday that he wanted to meet with his Chinese counterpart, Xi Jinping, to discuss Beijing’s proposals for ending the conflict.
“China historically respects our territorial integrity, and it should therefore do everything for Russia to leave the territory of Ukraine,” he told a news conference, adding that he believed a meeting with Xi would “benefit our countries and security in the world.”
He did not say if a meeting with had been arranged with the Chinese leader or give any indication of when it might take place, but he insisted his main goal was ensuring that China had not supplied weapons to Russia.
President Joe Biden and European leaders appeared skeptical about Beijing’s peace proposals.
Describing the idea as “just not rational,” Biden told ABC News on Friday that he had “seen nothing in the plan that would indicate that there is something that would be beneficial to anyone other than Russia.”
Speaking at a news conference in Estonia on Friday, NATO Secretary General Jens Stoltenberg also said that China did not “have much credibility because they have not been able to condemn the illegal invasion of Ukraine.”
At the same news conference European Commission President Ursula von der Leyen said that European leaders would look at the Chinese principles for peace “against the backdrop that China has already taken sides.”