Japanese Senior Deputy Minister for Foreign Affairs Shigeo Yamada, second from right, speaks to Chinese Vice Foreign Minister Sun Weidong, second left, during the Japan-China security dialogue at the foreign ministry in Tokyo on Feb. 22, 2023. 鈥 REUTERS

BEIJING聽鈥 China has lodged a diplomatic complaint with Japan regarding the visit by a high-ranking official of Japan鈥檚 ruling Liberal Democratic Party (LDP) to Taiwan, the Chinese foreign ministry said on Monday, as ties between the East Asian nations strain.

鈥淐hina is firmly opposed and has lodged solemn representations with the Japanese side,鈥 spokesperson Lin Jian said, urging Japan to 鈥渞eflect deeply on its mistake鈥.

Taiwan President Lai Ching-te received the LDP鈥檚 executive acting secretary general Koichi Hagiuda in the presidential office in Taipei on Monday, and聽urged closer cooperation between Taipei and Tokyo to help maintain regional stability and advance a 鈥渇ree and open Indo-Pacific鈥.

Mr. Lai said he hoped the two sides would 鈥渏oin hands, stay united and support each other鈥 to deepen cooperation in areas including national strategy, regional partnerships, economic security, and high-tech industries.

He urged democracies to 鈥渟tand together so as not to be picked off one by one.鈥

Mr. Hagiuda鈥檚 visit comes with聽diplomatic ties between Tokyo and Beijing at their lowest in years after Japanese Prime Minister Sanae Takaichi suggested last month a hypothetical Chinese attack on Taiwan could trigger a military response from Tokyo.

China responded vehemently and has been pushing for the Japanese leader to retract her statement. 鈥 Reuters