"I am pleased to inform you that I have just named General/Secretary John F Kelly as White House Chief of Staff," Trump told his more than 34.8 million followers on twitter soon after his return from New York.
"He is a Great American and a Great Leader. John has also done a spectacular job at Homeland Security. He has been a true star of my Administration," Trump said.
Scaramucci was appointed the new White House Communication Director on July 21.
Soon after, Sean Spicer had resigned as the White House Press Secretary in protest.
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Trump also promoted his Deputy Sarah sanders as the new White House Press Secretary.
Before being appointed as the White House Chief of Staff, Priebus was the chairman of the Republican National Committee, in which capacity he played a key role in Trump's presidential election.
He previously served as the former Commander of US Southern Command and was the commanding general of the Multi- National Force-West in Iraq from February 2008 to February 2009.
As Secretary of Homeland Security, Kelly has played a key role in the border security of the Trump Administration.
Over the last few weeks, Trump has expressed frustration over the White House leaks.
With a retired general in charge of his White House now, the president hopes to bring in some discipline and end the current mess inside the White House.