WASHINGTON (AP) — China has surged sales to Russia of machine tools, microelectronics and other technology that Moscow in turn is using to produce missiles, tanks, aircraft and other weaponry for use in its war against Ukraine, according to a U.S. assessment.

Two senior Biden administration officials, who discussed the sensitive findings Friday on the condition of anonymity, said that in 2023 about 90% of Russia’s microelectronics came from China, which Russia has used to make missiles, tanks and aircraft. Nearly 70% of Russia’s approximately $900 million in machine tool imports in the last quarter of 2023 came from China.

Chinese and Russian entities have also been working to jointly produce unmanned aerial vehicles inside Russia, and Chinese companies are likely providing Russia with nitrocellulose used in the manufacture of ammunition, the officials said. China-based companies Wuhan Global Sensor Technology Co., Wuhan Tongsheng Technology Co. Ltd. and Hikvision are providing optical components for use in Russian tanks and armored vehicles.