The international system has been ruptured. Russia’s invasion of Ukraine, gridlock at the un, growing American mercantilism and paralysis at the World Trade Organisation (WTO) have all contributed to the breakdown of the post-cold-war order of multilateral institutions, rules and conventions.

The security, prosperity and resilience the old system delivered depended heavily on the commitment of its core, the United States of America. As that indispensable nation has adjusted its commitments to global institutions, the fragility of the post-cold-war system has been revealed.

To re-establish resilience, a new web of ad hoc co-operation is beginning to emerge. We are entering an era of “variable geometry” characterised by dynamic, overlapping, pragmatic coalitions, built around shared interests, and occasionally shared values, rather than shared institutions.

It may seem unusual to apply a hard engineering term to the soft arts of foreign policy, but each discipline is designed to build. And in the world of international affairs, a term that describes mechanisms that can adjust to changing environments is an apt description and a useful guide to action.

A prominent example of variable geometry is the “coalition of the willing”—the ad hoc group of nations which has come together to support Ukraine. NATO and the allies that comprise it have provided extraordinary support to Ukraine in its self-defence against Russian aggression, but NATO is unsuited to the task of providing post-conflict security guarantees, as is the UN. In contrast, the impact of a bespoke, rapidly assembled alliance has been impressive. In just six months, the coalition of the willing has begun planning for boots-on-the-ground support in anticipation of a ceasefire, which would have been impossible in larger multilateral forums.

In Europe, the new SAFE pact unites nations determined to fast-track defence procurement. By cutting through bureaucracy and pooling procurement, SAFE will enable partners to buy and build together at speed. This accelerates capability development, bolsters national defence industries and expands strategic autonomy.

To address the risks of sudden disruptions to global trade in critical minerals, Canada is bringing together like-minded nations to form a critical-minerals strategic alliance. The goal is to secure and diversify supply chains by investing in mining, stockpiling supplies and developing standards-based markets to guard against future shortages.

Expect such purpose-built alliances to continue to proliferate. Even when their webs of connection are small, these groups can have outsize impacts by cutting through bureaucracy, moving fast and reinforcing shared strategic interests. Difficult times require pragmatic responses. Countries that might not normally be considered “like-minded” will increasingly co-operate where they share specific goals and values on specific issues. For example, the new climate architecture could be an amalgam of trade rules anchored by the EU, technology standards centred in China and India, and nature-based solutions grounded in Brazil.

Instead of a single, reformed rules-based trading system, a mosaic of partial agreements and creative “docking” arrangements between blocs could develop. One option would be to bring together two of the world’s largest trading blocs, the EU and the Asia-centred CPTPP. Reaching consensus to reform the wto could take decades. But bringing together groups of countries that share a belief in free trade—grounded in basic standards for labour, the environment and data sovereignty—will be a faster way to make progress.

Though the growth of variable geometry risks fragmentation, duplication and potential inequities for those left outside these clubs, such concerns should be outweighed by the benefits of speed, adaptability and impact. These coalitions could ultimately prove more resilient to future shocks than the current hub-and-spoke system that is only as strong as its core. Variable geometry need not be static: successful coalitions will attract new joiners.

Nostalgia is not a strategy. We should not pine to go back to the world that was. We should focus on building something better. The twilight of multilateralism will be followed by the rise of plurilateralism. States that embrace variable geometry, weaving new networks and constructing pragmatic alliances, will be best placed to thrive in this new age.