National security adviser Jake Sullivan told reporters Tuesday that the U.S.’s number-one priority with respect to China when it comes to the war in Ukraine is that China not become militarily supportive of Russia through the provision of equipment. “Number two is that they not engage in wholesale or systematic undermining or evasion of U.S. sanctions,” he said while traveling to the North Atlantic Treaty Organization summit in Madrid.

“Thus far, we have not seen China act in a way inconsistent with those two principles and certainly not at scale with respect to the economic relationship,” Mr. Sullivan said.

Martin Chorzempa, an analyst with the Peterson Institute for International Economics, said that “export controls against Russia are working—with the help of China.”

In a Monday post on the PIIE’s website, Mr. Chorzempa cited data that China’s exports to Russia since the invasion have fallen 38% compared with the second half of 2021, versus an 8% drop in China’s overall exports during the same period.