"Please reply to this email with approx. 5 bullets of what you accomplished last week and cc your manager," Musk's message said.

Elon Musk on Monday said Saturday's email "was basically a check to see if the employee had a pulse and was capable of replying to an email."

A defiant threat by Elon Musk warning that federal employees will be given "a second chance" to respond to his email asking them to justify their jobs or risk termination is likely to spark another round of confusion across the U.