Meet John F. Kelly, Donald Trump's new White House chief of staff

Joshua Roberts | Reuters

Secretary of Homeland Security John Kelly speaks about border security during a press briefing at the White House in Washington, May 2, 2017.

It's official: Reince Priebus, Donald Trump's beleaguered chief of staff, is out.

The president took to Twitter on Friday evening to announce that his new chief of staff will be John F. Kelly, who is currently serving as the Secretary of Homeland Security.

"I am pleased to inform you that I have just named General/Secretary John F Kelly as White House Chief of Staff. He is a Great American ...," Trump tweeted to his more than 34 million followers, "... and a Great Leader. John has also done a spectacular job at Homeland Security."

Trump added: "He has been a true star of my Administration."

About Priebus, he wrote, "I would like to thank Reince Priebus for his service and dedication to his country. We accomplished a lot together and I am proud of him!"

TWEET

According to the Department of Defense, the four-star Marine general, 67, was born and raised in Boston, "enlisted in the Marine Corps in 1970, and was discharged as a sergeant in 1972, after serving in an infantry company with the 2nd Marine Division, Camp Lejeune, North Carolina."

After graduating from the University of Massachusetts in 1976, he became an officer in the Marine Corps. He served in various positions with the U.S. military over the years, including as Special Assistant to the Supreme Allied Commander in Belgium. He returned to the U.S. in 2001, becoming a brigadier general in 2002.

TWEET

Kelly also served a tour in Iraq and was eventually placed in charge of the United States Southern Command, a position he held until January 2016. That "had him in charge of military operations in 32 countries in the Caribbean, Central America and South America," according to PBS.

The article notes that Kelly was a staunch critic of President Barack Obama:

He has occasionally criticized the Obama administration's military policy, such as trying to close Guantanamo Bay and opening all combat roles to women. He argued that conditions in Gitmo are not as harsh as its opponents have alleged and that the military would be forced to lower its physical standards to allow women in combat roles.

Just a year after retirement, he was tapped by Trump to serve as the Secretary of Homeland Security. According to PBS, Kelly did not "openly endorse Donald Trump at any point throughout his campaign."

Kelly's new appointment comes just days after Anthony Scaramucci, Trump's newly assigned communications director, gave a scathing critique of Priebus' role in the administration. As The New Yorker reports, there was believed to be considerable friction between the two men:

While they have publicly maintained that there is no bad blood between them, Scaramucci and Priebus have been feuding for months. After the election, Trump asked Scaramucci to join his Administration, and Scaramucci sold his company, SkyBridge Capital, in anticipation of taking on a senior role. But Priebus didn't want him in the White House, and successfully blocked him from being appointed to a job until last week, when Trump offered him the communications job over Priebus's vehement objections.

Preibus, 45, previously served as the chairman of the Republican National Committee.

TWEET

"Reince is a good man. John Kelly will do a fantastic job," Trump told reporters who had traveled with him Friday on Air Force One. "General Kelly has been a star, done an incredible job thus far, respected by everybody. He's a great, great American. Reince is a good man."

Like this story? Like CNBC Make It on Facebook.

See also: Report: 20 percent of Americans could pay higher taxes under Trump's plan