WASHINGTON, April 27 (Xinhua) -- U.S. Secretary of Defense James Mattis said Friday that the United States will discuss with allies and the Democratic People's Republic of Korea (DPRK) the need for U.S. troops to stay stationed on the Korean Peninsula.

The army stationing issue is part of the problems that Washington will discuss in the negotiations with allies first and then with the DPRK, Mattis said while meeting with Polish Defense Minister Mariusz Blaszczak at the Pentagon.

He added that the United States "will build, through confidence-building measures, a degree of trust if it's going to go forward," referring to the dialogue with the DPRK on the denuclearization issue.

U.S. President Donald Trump in March threatened to withdraw troops from the Korean Peninsula in an attempt widely seen to pressure Seoul to make concessions in bilateral trade dialogues.

"We have a very big trade deficit with them, and we protect them," Trump said in a fund-raising speech in the U.S. state of Missouri. "We lose money on trade, and we lose money on the military."

The U.S. troops have stayed in South Korea ever since the signing of an armistice treaty at the end of 1950-1953 Korean War.

Bilateral relations have been strained over issues like defense burden sharing, the U.S. army's harassment of South Korean civilians and Seoul's initiative to take back the war-time command control from Washington, among others.