U.S. President-elect Donald Trump on Tuesday announced a spate of unconventional picks for key posts in his next government, including a Fox News host, a former spy chief and the world's richest man.

In nominating Fox News host and military veteran Pete Hegseth to be the next U.S. defense secretary — a post that has often gone to senior military brass and former top bureaucrats — Trump heralded the 44-year-old as "tough, smart and a true believer in America First."

"With Pete at the helm, America's enemies are on notice — Our Military will be Great Again, and America will Never Back Down," Trump wrote in a statement.