Russia has asked China for military equipment since its Feb. 24 invasion of Ukraine, the Financial Times and Washington Post reported on Sunday, citing U.S. officials.
U.S. National Security advisor Jake Sullivan will be in Rome on Monday to meet with China's top diplomat Yang Jiechi, the White House said earlier.
Russia, which calls its action in Ukraine a "special operation," and China have tightened cooperation as they have come under strong Western pressure over human rights and a raft of other issues.
Beijing has not condemned Russia's attack and does not call it an invasion, but has urged a negotiated solution.
The White House's National Security Council declined to comment.
The Washington Post said the unidentified U.S. officials did not state the kind of weaponry that had been requested or how China had responded.
