The Prime Minister’s visit to Japan offers a useful starting point for a new discussion on what the UK’s strategy in Asia should be. That it coincided with North Korea’s latest missile launch was a graphic illustration of how trade and security are umbilically connected in the Asia Pacific – and a curtain raiser on the type of dilemmas that the UK is likely to face as it develops its Asia policy.

The good news is that the UK’s national interest chimes with that of its allies. The alliances that Britain has already – defensive, commercial, bi-lateral and multi-lateral – are its best assets in the region. They are realpolitik-plus: that is, they are not only built around mercantilist self-interest but shared approaches to trade, open markets, international security and the preservation of the global commons. The first priority of UK strategy in Asia must be to ensure that these alliances are maintained and, where possible, bolstered – particularly in South and Southeast Asia.

It would be a mistake to overestimate the UK’s leverage in the Asia Pacific, notwithstanding the enhancement of its capabilities. The deployment of HMS Queen Elizabeth in 2021 will not alter the military balance of forces within the region. Nonetheless, such commitments, and the reinforcement of the Five Power Defence Agreement that such naval deployments intimate, do amplify the diplomatic presence that the UK already has in the region.

Recent joint exercises between the UK and its allies in Asia should be seen in that light. In October last year, RAF Typhoon fighter jets were sent to Japan to take part in the first ever joint drill with the Japanese Air Self-Defense Force. In August this year, the UK joined South Korea and US forces for joint military exercises that came in response to new missile tests by the regime in Pyongyang. In both cases, this is likely to be the prelude to further cooperation in security.

The point here is not that the UK brings indispensable skills or capabilities to its allies in this region; nor will North Korea or China be watching these manoeuvres with any sense of awe at the UK’s ability to project force in Asia. What matters is how such actions fit into the broader alliance system within the region as a whole, and how this is projected within Asia – notably in the South China Sea and in the Indian Ocean – and beyond.

The active engagement of the UK reaffirms the fact that there is a perceived community of interest among nations – that are, broadly speaking, liberal, capitalist, democratic and under the rule of the law – that transcends the geographic dividing line between East and West. In practical terms, the support of another seat-holder on the UN Security Council means that internationally-agreed actions like imposing new sanctions on North Korea through the UN become easier when the occasion arises. Conscious of appearing intransigent or “rogue-friendly”, such collective action puts pressure on China, and Russia, to collaborate in these efforts rather than exercise their vetoes in the Security Council.

A close relationship with the United States remains the foundation of almost every action that the UK takes abroad and this applies in Asia too. It therefore makes sense to coordinate the UK’s actions in Asia around those of the US, much as Japan and other key regional allies do. On the basis of that calculation, the Prime Minister used her visit to Japan to urge China to do more on North Korea – an increasingly familiar refrain from the White House that also plays well with the Japanese.

Yet such actions are not cost free. Yet the fact that this provoked a “furious” reaction from Chinese state media is another illustration of how improved relations with one regional power can come at the expense of another.

China is, of course, the elephant in the room in any foreign policy discussion of economic and security linkages in the Asia Pacific. The UK continues to seek inward investment and close relations with Beijing. As Singapore, Vietnam and Australia have recently discovered, aligning too closely with the US or endorsing the decisions of international arbitration tribunals against Chinese maritime claims entails costs.

Engaging more in Asia opens the doors to new opportunities. But it also implies making difficult choices and choosing sides. In future years, as its new aircraft carriers enter Asian waters, the UK must tread lightly, act prudently, and spend its limited capital wisely.