While it was difficult to determine the current level of ammunition stocks at Russia’s disposal, O’Brien said, «They have certainly used a lot more than they originally thought.»

Russia was firing about 20,000 artillery shells a day, a senior US official told NBC News in November. Even Russia’s own mercenary force, the Wagner Group, has accused Moscow of depriving them of projectiles. In November, US officials also said that North Korea was covertly supplying Russia with large numbers of artillery shells, which experts said suggested Russia was running out of them.

“All the artillery you have is just empty tubes if you can’t shoot ammunition out of them,” said Frank Ledwidge, a senior professor of law and strategy at the University of Portsmouth in England.

“We can absolutely guarantee that this would extend Russia’s artillery capabilities into at least next year, even if they don’t give anything else,” Ledwidge added.

But «Beijing is stuck in a difficult position,» Fiala said.

While China has refrained from condemning the invasion and last week presented a peace plan that the West quickly rejected, it has so far practiced a careful balancing act.

Russia’s victory and stability were ultimately in Chinese interest, Fiala said, but Western sanctions that could be imposed if it increased its support may make Beijing think twice.

kyiv will no doubt be watching closely and perhaps renewing its bid for more support from its own allies, experts said.

The «Ukrainians will probably use it as an argument for their NATO backers to say they have to get us more, quickly, before the Chinese really start giving real support to the Russians,» O’Brien said.

leila sackur contributed.