Japan has issued a pointed rebuke to China’s military build-up, describing its arsenal as “huge” and a source of regional instability. The criticism, delivered by the Japanese foreign ministry on Tuesday, comes as the United Kingdom formalised a security pact with Tokyo aimed at reinforcing stability in the Indo-Pacific.
The Japanese statement, released ahead of a summit with British Prime Minister Keir Starmer, directly challenged Beijing’s expansion of its nuclear and conventional forces. “China’s huge arsenal, including its rapid increase in nuclear warheads, is a matter of grave concern for the international community,” the ministry said. It called on China to exercise restraint and enhance transparency in its military posture.
Tokyo’s language marks a significant hardening of rhetoric against Beijing, which in recent years has intensified its presence in the East China Sea and around Taiwan. Japan’s position aligns with growing concerns among Pacific nations about the pace of China’s military modernisation.
Separately, the United Kingdom and Japan announced a new bilateral security agreement, described as a “landmark pact” to bolster cooperation in the region. The deal, signed in London, commits both nations to closer naval patrols, joint exercises, and intelligence sharing. It also includes provisions for co-development of next-generation fighter jets and cyber defence capabilities.
British Prime Minister Keir Starmer called the agreement “a vital step in securing a free and open Indo-Pacific.” He added that the partnership would “deter aggression and uphold the rules-based international order.” Japan’s Prime Minister, in a joint statement, welcomed the UK’s increased engagement, noting that “shared values and strategic alignment are essential for regional peace.”
The pact is the latest in a series of UK moves to deepen ties in the region since leaving the European Union. It follows a similar agreement with Australia under the AUKUS framework and a trade deal with New Zealand. Analysts see the UK’s pivot as an effort to counterbalance Beijing’s influence and preserve Western access to vital sea lanes.
China’s foreign ministry responded to Japan’s rebuke with a statement accusing Tokyo of “stoking confrontation” and “misrepresenting” China’s defensive policies. “China’s military development is defensive in nature, and our nuclear arsenal is kept at the minimum level required for national security,” a spokesperson said. Beijing also objected to the UK-Japan pact, calling it “an attempt to create exclusive blocs” that undermine regional trust.
The developments come amid heightened tensions over Taiwan, where China has increased military drills. Japan and the UK both maintain unofficial ties with Taipei, and the new pact includes a clause on maintaining peace across the Taiwan Strait.
Strategic experts have noted that the UK’s support provides Japan with diplomatic cover as it takes a firmer line against Beijing. “For Tokyo, having a European nuclear power publicly back its stance is a significant boost,” said Professor Naoko Ishii of the University of Tokyo. “It signals that this is not just a bilateral dispute but a matter of global concern.”
The UK’s return to the region, after decades of focus on Europe and the Middle East, has been met with cautious approval by other Pacific nations, including Australia and the United States. However, some analysts warn that deepening military ties could fuel an arms race in the region.
Japan’s defence budget is set to double over the next five years, reaching 2% of GDP, partly in response to China’s advances. The UK’s commitment to deploy a carrier strike group to the Pacific by 2025 further underscores the shift.
As the standoff continues, the UK-Japan pact is expected to serve as a template for further security arrangements. Both countries have signalled openness to expanding the framework to include other like-minded nations.
