WASHINGTON, July 28 -- U.S. President Donald Trump tweeted Friday he had named John Kelly, Secretary of Homeland Security, as the new White House Chief of Staff.

"I am pleased to inform you that I have just named General/Secretary John F Kelly as White House Chief of Staff," Trump said.

"He is a great American and a great leader. John has also done a spectacular job at Homeland Security," Trump said, adding that Kelly has been "a true star of my administration."

"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!" Trump said of his outgoing chief of staff.