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.

Billionaire's estranged daughter has used rival social media platforms to attack Trump's anti-transgender executive order, and her dad's salute.