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.

"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 threatened to fire even more federal workers if they did not respond to his email demanding a list of five tasks completed.