The move clearly shows Musk's growing influence on the Trump administration.

Musk, who campaigned for Trump in the final weeks of the 2024 race, was not scheduled to be on the call but walked into the room and greeted Zelenskyy, sources told NBC News.

He was not part of a substantive conversation between the two leaders, the person said.

Neither Trump nor Zelenskyy had confirmed earlier that Musk was on the call.

The Ukrainian President shared details of his telephonic conversation with Trump and wrote on X: " I had an excellent call with President
@realDonaldTrump and congratulated him on his historic landslide victory—his tremendous campaign made this result possible. I praised his family and team for their great work."

He said: "We agreed to maintain close dialogue and advance our cooperation. Strong and unwavering U.S. leadership is vital for the world and for a just peace." 

In a separate post, Zelenskyy, earlier, congratulated Trump on his US Presidential poll victory.

The Ukrainian President posted on X: "Congratulations to @realDonaldTrump on his impressive election victory!" "I recall our great meeting with President Trump back in September, when we discussed in detail the Ukraine-U.S. strategic partnership, the Victory Plan, and ways to put an end to Russian aggression against Ukraine," he said.

"We look forward to an era of a strong United States of America under President Trump’s decisive leadership. We rely on continued strong bipartisan support for Ukraine in the United States," he said.