(Adds background on Whitaker, Trump quotes, paragraphs 2-7)

WASHINGTON, Nov 20 (Reuters) - President-elect Donald Trump chose Matthew Whitaker on Wednesday as his nominee to be U.S. ambassador to NATO, selecting a loyalist who briefly served as acting attorney general during Trump's first White House term.

"Matt is a strong warrior and loyal Patriot, who will ensure the United States' interests are advanced and defended. 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," Trump said in a statement.

U.S. relations with the North Atlantic Treaty Organization were strained during Trump's first term, as the Republican president criticized NATO and accused European members of spending too little on defense.

Whitaker has been actively involved with the America First Policy Institute, a right-leaning think tank that has been working closely with Trump's campaign to shape policy for his second term.

Trump has offered few

foreign policy

specifics, but supporters say the force of his personality and his “peace through strength” approach will help bend foreign leaders to his will and calm what Republicans describe as a "world on fire" amid conflicts in Ukraine and the Middle East.

"I have full confidence in Matt’s ability to represent the United States with Strength, Integrity, and unwavering Dedication," Trump said in a statement.

"I look forward to working closely with him as we continue to promote PEACE THROUGH STRENGTH, Freedom, and Prosperity around the World."

(Reporting by Doina Chiacu and Ismail Shakil; Editing by)

((doina.chiacu@thomsonreuters.com; 202-898-8322;))