The U.S. is determined to enforce sanctions over North Korea’s efforts to “assist” Russia’s invasion of Ukraine, the State Department said Monday.

Spokesperson Matthew Miller made the remarks in answer to questions about reports that a Russian military aircraft made an unannounced visit to Pyongyang last week, days after the Kremlin’s defense chief visited the DPRK to attend a large-scale military parade and weapons expo.

“We have made clear our concerns about cooperation between Russia and North Korea. We have made clear our concerns about North Korea seeking to assist Russia in its aggression in Ukraine,” Miller said. “And we