U.S. Deputy Secretary of State Wendy Sherman and her Japanese counterpart, Takeo Mori, have underscored trilateral cooperation involving South Korea, after a territorial dispute between the two Asian nations led Mori to pull out of a planned three-way news conference a day before.

While agreeing that the U.S.-Japan alliance is the cornerstone of peace and security in the Indo-Pacific region, the two officials on Thursday "reaffirmed the importance of U.S.-Japan-Republic of Korea trilateral cooperation, which seeks to tackle the global challenges of the 21st century," the State Department said in a press release.

The Republic of Korea is the formal name for South Korea.