President Donald Trump rarely sends staff members packing without a parting jab. On occasion, as with Linda McMahon, the former Small Business Administration chief, he praises them as they’re headed out the door. But either way, Trump seems keenly aware of the public’s perception of the constant departures from his administration. “He’s always thinking optics,” said former White House staffer Cliff Sims, who wrote a book about the Trump White House. This week, Trump announced the exit of U.S. Homeland Security Secretary Kirstjen Nielson with a curt tweet. On several occasions, the president has blindsided his own aides by announcing someone’s exit.