TOKYO (AP) — The leaders of Japan and Vietnam expressed serious concern on Wednesday about the situation in the South China Sea and any unilateral actions aimed at altering the status quo, and agreed to work together to sustain free and open sea lanes as tensions escalate in the region amid China’s rise.

Vietnamese Prime Minister Pham Minh Chinh is the first foreign leader to visit Japan for talks with new Prime Minister Fumio Kishida, who took office in October.

Kishida told Chinh in his opening remarks that “Vietnam is an important partner who holds a key to achieving ‘a free and open Indo-Pacific,'” a vision aimed at countering China’s increasingly assertive territorial claims in the disputed region. He did not mention China by name.

The two leaders “expressed serious concerns about the situation in the South China Sea and any unilateral attempts to change the status quo and increase tensions,” they said in a joint statement, without naming any country.

They reaffirmed the importance of sustaining peace, security, safety, freedom of navigation and overflights above the South China Sea, and the peaceful resolution of disputes in accordance with international law, according to the statement, released by Japan’s Foreign Ministry.

China, which claims most of the South China Sea as well as Japanese-held islands in the East China Sea, says it has the right to defend its sovereignty, security and development interests.

Japanese officials say Chinese vessels routinely violate Japanese territorial waters near the East China Sea islands, sometimes threatening fishing boats.

The two countries on Wednesday also confirmed a range of partnerships in areas such as COVID-19, infrastructure and climate change. Japan will also support a strengthening of Vietnam’s maritime law enforcement capabilities by accelerating aid for construction of patrol vessels.

On Tuesday, Japan and Vietnam signed a cybersecurity agreement. In September, the two countries struck a deal allowing Japan to provide defense equipment and technology to Vietnam. Details of the transfer of specific equipment, possibly naval vessels, are still being discussed.

Vietnam is the 11th nation with which Japan has signed a defense equipment and technology transfer deal as Tokyo seeks to support its own struggling defense industry.

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