Japan’s Defence Minister Taro Kono and US counterpart Mark Esper agreed in Guam on Saturday that they will keep China’s maritime assertiveness in the South and East China seas in check. “As for the South and East China seas, we confirmed that Japan and the United States will strongly oppose countries unilaterally changing the status quo by force,” Kono said in an online press conference after meeting with Esper at Andersen Air Force Base. Beijing is involved in territorial disputes with Tokyo and a number of other Asian neighbours in the waters. Kono said Esper had confirmed that Article 5 of the US-Japan security treaty applies to the East China Sea islets, known as the Senkaku islands in Japan and the Diaoyu islands in China. Article 5 stipulates Washington’s commitment to defend Tokyo. Pentagon officials said China fired four ballistic missiles into the South China Sea on Wednesday in an apparent warning to US reconnaissance planes flying near areas where Beijing has been conducting naval drills. Kono told Esper the launch could help destabilise the region and that he will monitor the situation with concern, according to a Japanese defence ministry official. At the outset of the talks, Esper condemned China’s behaviour in the waters, saying, “We are steadfast in our opposition to Beijing’s destabilising activities in the region.” Kono said in response, “I think the world has been changing drastically. Not just because of Covid-19 , but because there are some attempts to change the status quo by force and coercion.” The Japanese minister said he and Esper also agreed during their first direct talks since January to cooperate toward the establishment of a new missile defence system after Tokyo decided in June to halt plans to deploy the US-developed Aegis Ashore missile defence system. The planned deployment of the Aegis Ashore system, originally intended to strengthen Japan’s deterrence against North Korea’s missile threats, was scrapped as Tokyo found it potentially costly and time-consuming upgrades would become necessary to ensure the safety of nearby residents during a missile interception. Why are tensions running high in the South China Sea dispute? Kono said he explained to Esper about the ongoing talks at Japan’s National Security Council on alternative options. Tokyo is set to indicate a policy on the new missile defence system in September. In a related move, the ruling Liberal Democratic Party submitted a proposal this month for Japan to consider “possession of the ability to intercept ballistic missiles and others even in the territory of an opponent,” a controversial suggestion in light of Japan’s war-renouncing Constitution. Kono and Esper also discussed enhanced cooperation between the two allies in fields such as outer space, cyberspace and electronic warfare, the official said. In Tokyo, Kono met US Chief of Space Operations General John Raymond on Wednesday when the latter was making his first visit to Japan since the creation of the Space Force and his appointment in December last year. Kono is on his first overseas trip since February, when he attended an international conference in Germany.