John Kelly, the former secretary of the Department of Homeland Security, was sworn in as White House chief of staff Monday morning.

President Trump announced Friday that Kelly would become his new chief of staff, replacing Reince Priebus. Priebus served in the position for six months, but quietly resigned Thursday.

"He will do a spectacular job, I have no doubt, as chief of staff," Trump said of the retired Marine Corps general, after his swearing in. "What he's done in terms of Homeland Security is record shattering. You look at the border. You look at the tremendous results we've had, and you look at the spirit. And with a very controversial situation, there's been very little controversy, which is pretty amazing by itself.

"I want to congratulate you on having done a fantastic job, general, and we look forward to, if it's possible, an even better job as chief of staff."

Kelly was sworn in at 9:30 a.m., and will attend a Cabinet meeting with the president.