U.S. Deputy Secretary of State Wendy Sherman and her Japanese counterpart Takeo Mori on Thursday underscored the trilateral cooperation involving South Korea, after a territorial dispute between the two Asian allies led Mori to pull out of a planned three-way press 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 "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.

Republic of Korea is the formal name of South Korea.

Japan's Vice Foreign Minister Takeo Mori (R) and U.S. Deputy Secretary of State Wendy Sherman bump elbows as they meet on July 20, 2021, in Tokyo. (Pool photo)(Kyodo)

Sherman, for her part, stressed the U.S. commitment to defending the rules-based international order amid China's growing assertiveness in the region.

She also expressed the "unwavering U.S. support" for those working toward the peaceful restoration of Myanmar's path to democracy following the February military coup, according to the department.

Recently, an American journalist sentenced to 11 years in prison by a court in Myanmar was freed and flown out of the military-run country, a move that was facilitated by Yohei Sasakawa, chairman of the philanthropic Nippon Foundation and Japan's special envoy for national reconciliation in Myanmar, and others.

Sherman and Mori also discussed North Korea and their shared commitment to the complete denuclearization of the Korean Peninsula.

The bilateral talks took place a day after the trilateral meeting among the two and South Korea's First Vice Foreign Minister Choi Jong Kun was held at the State Department.

A joint press conference was planned after the trilateral talks, but the Japanese government decided not to attend in an expression of protest against South Korea over a recent visit by the country's top police official to a pair of Seoul-held, Tokyo-claimed islets in the Sea of Japan.

File photo shows (From L) South Korean First Vice Foreign Minister Choi Jong Kun, Japan's Vice Foreign Minister Takeo Mori and U.S. Deputy Secretary of State Wendy Sherman pose for a photo in Tokyo on July 21, 2021. (Kyodo)

In addition to the dispute over the islets, known as Takeshima in Japan and Dokdo in South Korea, the relationship between Tokyo and Seoul has remained sour over wartime compensation issues.

The gathering on Wednesday was the first trilateral vice-foreign ministerial-level meeting since Japanese Prime Minister Fumio Kishida took office in October. The joint press conference was apparently a chance to showcase their unified stance in the face of North Korean nuclear threats and other challenges in the region.