The US State Department says Washington's top diplomat will directly convey concerns to Beijing about Chinese materials being used in Russia to produce weapons.
State Department spokesperson Matthew Miller said on Tuesday that Secretary of State Antony Blinken is expected to raise the issue during an upcoming trip to China.
Miller said the United States has long made clear to China its concerns about any actions to support Russia's war in Ukraine.
He said this includes not just direct military support, but "any steps taken by Chinese companies to reconstitute Russia's defense industrial base."
Miller said that in recent months, the US has seen materials moving from China to Russia, which have been used to rebuild that industrial base and produce arms that are showing up on the battlefield in Ukraine.
He said the US is "incredibly concerned about that."
US media have quoted senior US government officials as saying that China provided Russia with materials, such as turbojet engines and technology for cruise missiles, as well as engines for drones.
The reports say that in 2023, about 90 percent of the microelectronics used by Russia to make missiles, tanks and aircraft were imported from China.