The U.S. Air Force has again flown heavy B-1B bombers over the Korean Peninsula, this time just days ahead of Donald Trump's inaugural visit to Asia as president, with Japan set to be his first stop on Sunday.

Two B-1Bs from Andersen Air Force Base on Guam conducted sequenced bilateral missions Thursday with South Korean Air Force fighter jets and Air Self-Defense Force warplanes, the U.S. Pacific Air Forces said in a statement Friday.

"The two B-1B Lancers ... transited south of Korea and west of Japan to integrate with Koku Jieitai (Japan Air Self-Defense Force) fighters," the statement said. "The Lancers then transited overland to Korea to integrate with Republic of Korea fighters in the Yellow Sea. Upon completion of bilateral integration, the aircraft return to their respective home stations."