Musk, 53, spoke to a crowd of Trump supporters at Capital One Arena in Washington, D.C., after Trump was sworn in at the U.S. Capitol. While thanking the supporters, Musk put his right hand over his heart, then extended his arm out with his palm down. He then turned around and repeated the gesture.

Elon Musk, the world's richest man, standing behind a podium bearing the Seal of the President of the United States, on Monday twice gave what scholars, journalists and rights groups said was a Hitlergruß,