President-elect Donald Trump on Wednesday announced the appointment of former acting Attorney General Matt Whitaker to serve as U.S. ambassador to the North Atlantic Treaty Organization (NATO).

"Matt is a strong warrior and loyal Patriot, who will ensure the United States' interests are advanced and defended," Trump said. "Matt will strengthen relationships with our NATO Allies, and stand firm in the face of threats to Peace and Stability - He will put AMERICA FIRST."

Whitaker served as acting attorney general after the resignation of Jeff Sessions and was a frequent figure on the Trump campaign trail. He previously served as the U.S. Attorney for the Southern District of Iowa.

Trump has previously tussled with NATO members, aiming to convince them to meet their defense spending targets.