Early Tuesday, Ukrainian President Volodymyr Zelenskyy posted on his Telegram account a purported video of a Chinese national who had been captured by Ukrainian troops.

“Our military captured two Chinese citizens who fought in the Russian army,” Zelenskyy said. “This happened on the territory of Ukraine—in the Donetsk region. There are documents of these prisoners, bank cards and personal data.”

Additionally, Zelenskyy said, “We have information that there are significantly more Chinese citizens in the units of the occupier than two.”

He said Ukrainian intelligence agencies are “clarifying all the facts.”

If what he suspects is true, it undermines Beijing’s public calls for a ceasefire to end the fighting in Ukraine.

Ukrainian Foreign Minister Andrii Sybiha said he had “summoned China’s chargé d’affaires” to explain why the Chinese nationals were fighting with Russian forces in Ukraine.

Sybiha wrote on X, “We strongly condemn Russia’s involvement of Chinese citizens in its war of aggression against Ukraine, as well as their participation in combat against Ukrainian forces.”

In addition to embarrassing the Chinese government, the incident raises a much bigger international issue — are two of the world’s biggest military powers, Moscow and Beijing, teaming up to continue an invasion of a sovereign country?

Another key question is: How this will impact the response of western countries trying to help Ukraine?

“This definitely requires a reaction,” Zelenskyy wrote. “A reaction from the United States, Europe and everyone in the world who wants peace.”