U.S. Secretary of State Marco Rubio meets Japanese Foreign Minister Iwaya Takeshi and South Korean Foreign Minister Cho Hyun at the Lotte New York Palace Hotel, on the sidelines of the 80th United Nations General Assembly in New York City, U.S., September 22, 2025. REUTERS/Bing Guan/Pool

SEOUL (Reuters) -The foreign ministers of South Korea, Japan and the United States expressed concern about increasingly frequent destabilising activities around Taiwan in a joint statement issued after their meeting.

The three also expressed strong opposition to "unlawful maritime claims" in the South China Sea and attempts to enforce such claims, the statement said.

The statement did not specifically mention China, but comes amid simmering tension between Beijing and Washington and its allies over the disputed South China Sea.

Taiwan's foreign ministry welcomed the expression of concern.

Taiwan will cooperate with the United States, Japan, South Korea and other like-minded partners to ensure peace and stability in the Taiwan Strait and Indo-Pacific, ministry spokesperson Hsiao Kuang-wei told reporters in Taipei.

China claims almost the entire South China Sea, overlapping the exclusive economic zones of Brunei, Indonesia, Malaysia, the Philippines and Vietnam. Unresolved disputes have festered for years over ownership of various islands and features.

U.S. Secretary of State Marco Rubio, South Korean Foreign Minister Cho Hyun and Japanese Foreign Minister Iwaya Takeshi met in New York on Monday and also discussed the three countries' continued commitment to ending North Korea's nuclear programme, their joint statement said.

China, which views the democratically-governed island as its own territory, has stepped up its military activities nearby, including staging war games. Taiwan's government rejects China's territorial claims.

(Reporting by Jack Kim and Ju-min Park; Additional reporting by Ben Blanchard in Taipei; Editing by Christian Schmollinger, Jamie Freed and Shri Navaratnam)