When Ukrainian President Volodymyr Zelensky called to congratulate President-elect Donald Trump on his successful White House run, an unexpected visitor dropped in on the conversation: Elon Musk, who has been promised a role in the new administration.

Musk's appearance on the call, which was first reported by Axios, wasn't coordinated, according to people familiar with the conversation, but he happened to walk into the room right as Trump and Zelensky were speaking.