Trump picks retired General James Mattis as Defense Secretary

"We are going to appoint 'Mad Dog' Mattis as our Secretary of Defence. But we're not announcing it until Monday so don't tell anybody," Trump said on Thursday at a rally in Cincinnati, kicking off his post-election 'Thank You' tour.

"They say he's the closest thing to General George Patton that we have and it's about time." he said.

Mattis, who continued to rise through the ranks and establish his credentials as a military thinker, has said that Washington lacks an overall strategy in the Middle East, opting to instead handle issues in an ineffective one-by-one manner.

Last year, he said responding to "political Islam" was the major security issue facing the US, The Washington Post reported.

He emerged as the top contender for Pentagon chief soon after Trump won the White House.

They met in New Jersey on November 19, with media reporting that Trump was impressed by Mattis' resume.

"The president-elect is smart to think about putting someone as respected as Jim Mattis in this role," said a former senior Pentagon official.

"He's a warrior, scholar and straight shooter -- literally and figuratively. He speaks truth to everyone and would certainly speak truth to this new commander-in-chief," the official said.

US media speculated that an extensive knowledge about the Middle East and a tough stance against extremism helped Mattis get the job.

Since the US law prohibits military officers from becoming Defense Secretary within seven years of retirement, Mattis must acquire a special waiver from the Congress to become eligible.

Congress has granted a similar exemption just once, when General George C. Marshall was appointed to the job in 1950.

Mattis, 66, enlisted in the military in 1969, was promoted through the ranks for his performances in the first and second Gulf wars and the Afghanistan War.

He occasionally has come under scrutiny for impolitic remarks. Most notably, he said in 2005 during a panel discussion in San Diego that "it's fun to shoot some people" and "I like brawling", drawing criticism from the Marine commandant at the time, General Michael Hagee.

Like Trump, Mattis favours a tougher stance against US adversaries abroad, especially Iran.

The General in April said that while security discussions often focus on terrorist groups such as the Islamic State or Al Qaeda, the Iranian regime is "the single most enduring threat to stability and peace in the Middle East".

Known as "Mad Dog" and "Warrior Monk", Mattis retired as chief of US Central Command in 2013.