Top diplomats from the Group of Seven countries leveled one of their strongest warnings yet against China, cautioning Beijing to stop helping Russia wage its war against Ukraine.

“We’ve made very clear to China - and many other countries have as well - that they should not be supplying Russia with weapons for use in its aggression against Ukraine,” US Secretary of State Antony Blinken told reporters in Capri Friday after a meeting of the G-7 foreign ministers.

“It’s allowing Russia to continue the aggression against Ukraine and it’s also helping Russia overall rebuild its defense forces and defense capacity,” he said.

Even though China has sought to portray itself as mostly neutral in the face of Russia’s invasion of Ukraine, it’s established a deep alliance with Moscow as part of what Xi Jinping and Vladimir Putin termed a “no limits” friendship two years ago.

Ukraine’s allies, including the US, have accused China of supporting Russia with optics, nitrocellulose, microelectronics, and turbojet engines. Bloomberg reported earlier this month that Beijing was also providing the Asian nation with satellite imagery for military purposes, as well as microelectronics and machine tools for tanks.

“We express our strong concern about transfers to Russia from businesses in the People’s Republic of China of dual-use materials and weapons components that Russia is using to advance its military production,” according to the G-7 communique. “This is enabling Russia to reconstitute and revitalize its defense industrial base, posing a threat both to Ukraine and to international peace and security.”

Ukraine is struggling to fend off military pressure from Russia in the face of a lack of ammunition and military equipment. President Volodymyr Zelenskiy has been calling for more air defense systems as Kremlin troops exploit the country’s weakness to step up missile attacks on power stations, electricity grids and residential areas.

“When China establishes an ever-closer relationship with Russia, which carries out an unlawful war of aggression, then we cannot accept this,” German Foreign Minister Annalena Baerbock told reporters on Friday in Capri. “We call on China to use its influence on Putin. In no case can we accept that any country in the world fires up Putin’s war machinery.”

Zelenskiy will speak with NATO defense ministers on Friday when he’s expected to ask for more air defense support. EU foreign and defense ministers will meet on Monday to discuss the topic.

“China can’t have it both ways,” Blinken said. “To have positive friendly relations with countries in Europe and at the same time be fueling the biggest threat to Europe since the end of the cold war.”