NASA Administrator Bill Nelson told Semafor’s Burgess Everett Friday that a Wall Street Journal report about calls between SpaceX founder Elon Musk and Russian President Vladimir Putin  “should be investigated.”

“I don’t know if that story is true,” Nelson said. “If it’s true there have been multiple conversations with Elon Musk and the president of Russia, then that would be concerning, particularly for NASA and the Department of Defense,” he added.

SpaceX is a key commercial partner for NASA: On Friday, NASA’s Crew-8 mission members returned to Earth on a SpaceX capsule. Speaking at Semafor’s World Economy Summit in Washington, DC, Nelson stressed that the agency was nonpartisan and praised his dealings with SpaceX CEO Gwynne Shotwell. The NASA head said that Musk largely leaves her to run the company, which he added has “been phenomenally successful.”