Trump names ‘Mad Dog’ defence secretary – Bye Bye ISIS

Mattis, 66, served more than four decades in the Marine Corps and is known as one of the most influential military leaders of his generation, a strategic thinker who occasionally drew rebukes for his aggressive talk. Since retiring, he has served as a consultant and as a visiting fellow with the Hoover Institution, a think tank at Stanford University.

Like Trump, Mattis favors a tougher stance against U.S. adversaries abroad, especially Iran. The general, speaking at the Center for Strategic and International Studies 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.” The 66-year-old retired from the Marine Corps in 2013, having served as the commander of the US Central Command.

Nicknamed “Mad Dog”, he was referred to by President-elect Mr Trump as “a true general’s general”

But, while his service record is mostly respected, there are concerns about his lack of experience in diplomacy. There is also concern about some of his other activities, including serving on the board of troubled biotech firm Theranos. The Washington Post reported that Theranos founder Elizabeth Holmes had tried to get him to intervene after a Pentagon official questioned the company’s selling of its technology without approval from the Food and Drug Administration.

Theranos promised new-age blood-testing technology but had to invalidate two years of results after the reliability of its methods were questioned. Mr Mattis also said in 2005 that it was “fun to shoot some people”.

He told a forum in San Diego: “Actually, it’s a lot of fun to fight. You know, it’s a hell of a hoot. It’s fun to shoot some people.I’ll be right up front with you, I like brawling.”

Mr Mattis added: “You go into Afghanistan, you got guys who slap women around for five years because they didn’t wear a veil.

“You know, guys like that ain’t got no manhood left anyway, so it’s a hell of a lot of fun to shoot them.”