The splash of hard news came during a sea of soaring -- and then blunt -- rhetoric from the 70-year-old Republican billionaire, who was speaking at his first post-election event following days of meetings about forming his cabinet.

"We are going to appoint 'Mad Dog' Mattis as our secretary of defense," Trump told cheering supporters in Cincinnati, referring by nickname to the four-star Marine general who headed the US Central Command, with authority over troops in Iraq and Afghanistan.

"He's our best. They say he's the closest thing to (World War II) general George Patton that we have," Trump said, apparently divulging his pick days ahead of schedule as his transition team had already said there would be no more cabinet announcements this week.

Mattis will require both Senate confirmation and a special waiver of a law that bans uniformed military officers from serving as secretary of defense for seven years after leaving active duty.

At least one Democrat, Senator Kirsten Gillibrand, already signaled she will oppose the waiver.

"Civilian control of our military is a fundamental principle of American democracy," the senator tweeted from New York.

Trump's surrounding himself with military figures -- he has picked retired general Michael Flynn to be his national security advisor and is considering retired general David Petraeus for secretary of state -- has unnerved some observers who point to America's long tradition of civilian government.

Copyright AFP (Agence France-Presse), 2016