"Elon Musk is right. The Pentagon, with a budget of $886 billion, just failed its 7th audit in a row. It’s lost track of billions," Sanders wrote. "Last year, only 13 senators voted against the Military Industrial Complex and a defense budget full of waste and fraud. That must change."

In the past, Sanders has been a vocal critic of Musk, clashing with him on wealth inequality, foreign relations and space travel.