WASHINGTON DC – Despite copping flak over the resignation of U.S. Defence Secretary Jim Mattis, President Donald Trump has defied critics by dismissing Mattis two months prior to his scheduled departure.

Mattis, a largely admired former U.S. general voiced concerns over policies being implemented by Mr Trump, including the United States withdrawal from Syria, and partial pull-out of Afghanistan. Both decisions have been taken by the White House against the advice of the Pentagon, and without consultation or the knowledge in advance, of allies working with the U.S. in these war zones.

Rather than cause disruption, Mattis gave notice to finish in February. The U.S. president however has ignored that and announced the appointment of Deputy Defence Secretary Patrick Shanahan who will take over next week, on 1 January 2019.

Shanahan, a former Boeing executive has only been in the defense department since July last year. Boeing is a significant contractor to the Pentagon.

A native of the state of Washington, Mr Shanahan did mechanical engineering and business degrees at the Massachusetts Institute of Technology. In 1986 he was recruited by Boeing as an engineer.

As usual, the important announcement of the early departure of Mattis, and the naming of his replacement, was done by the president himself on his personal Twitter page.

“I am pleased to announce that our very talented Deputy Secretary of Defense, Patrick Shanahan, will assume the title of Acting Secretary of Defense starting January 1, 2019. Patrick has a long list of accomplishments while serving as Deputy, & previously Boeing. He will be great!” tweeted the president.

It is unknown if Mr Mattis was advised prior to the tweet that his services will no longer be required.

Mr Trump at first portrayed his defense secretary’s resignation as a ‘retirement,’ however a strongly-worded resignation letter from Mattis put beyond doubt the reasons for his departure.