President Trump’s tariffs increase pressure on allies to reduce security dependence on the US

US tariffs add to the sense of an increasingly unpredictable and unreliable partner. Allies in Europe and the Pacific are questioning foundational assumptions about their security arrangements as a result.

Expert comment Published 15 April 2025 4 minute READ

Dr Samir Puri

Director, Global Governance and Security Centre

Alongside the market turmoil caused by the Trump administration’s shifting tariff policy, a parallel set of impacts are emerging in global security. The full effects may only be seen over time, but US tariffs threaten to produce outcomes that run contrary to Washington’s security objectives.

President Donald Trump assumes that he can afford to be overly assertive, even cavalier in his policies because other countries simply cannot afford to turn their backs on the US. But his constantly shifting tariff announcements have placed that belief under more stress than ever before. As trade with the US becomes more complex, unpredictable and expensive, some countries – including key US partners – may see additional incentives to rethink the extent of their security dependence on Washington.

The effects on international security are playing out differently among European and Asian allies, two regions that have relied on US security commitments for eight decades. But both are re-examining how committed this US administration is to their needs.

Europe

Europeans were jittery about President Trump’s commitment to their security before his election. His administration’s policies on NATO and the war in Ukraine increased their concerns. The US pursuit of peace talks with Russia, without European representation, has driven home the desire of the US to disengage from its commitments on the continent as rapidly as possible.

That has forced Europe’s leaders to take Trump’s 2024 campaign message seriously: it is now widely accepted that European governments must increase their defence budgets and assume the full burden of securing their continent.

European governments are already taking a ‘buy European’ approach to procurement.

That might be seen as a foreign policy triumph for President Trump: but the tariffs have now added a fresh economic rationale for an approach that decouples some European security dependencies from Washington. 

Many European governments have historically sourced weapons systems from the US, benefitting from its cutting-edge technology and economies of scale. But this could now change. Portugal, Canada and other US allies are now reconsidering purchases of the US-built F35 aircraft.

Tariffs will likely cause the cost of US defence products to rise, if for no other reason that US defence companies will pay more to procure essential components from global markets. 

And European governments are already taking a ‘buy European’ approach to procurement: a new €150 billion EU rearmament fund could exclude US companies from competing for contracts.

A reduction of defence exports to Europe was certainly not an outcome the Trump administration desired. Neither was the establishment of a European defence industry that might one day compete more effectively with the US on sales to other regions. This would go far beyond Trump’s current aim of Europe paying more for its own defence.

However much the US might object to being excluded from European procurement, the recent tariff turbulence can only support the rationale for Europe boosting investment in its own defence industrial base, which has struggled to make up for shortages caused by the delivery of military equipment to Ukraine.

Asia and the Pacific

In Asia the impact of tariffs uncertainty will be felt differently. US security partners in Asia and the Pacific are not involved in an active regional armed conflict like Ukraine. And there is no multi-party security pact comparable to NATO whose existence is threatened in the same way by the Trump administration. Instead, a series of individual security relationships exist between the US and Asia-Pacific states.

The Trump administration is also more invested in the region. Whereas confronting Russian forces in Europe is completely off the table for the US, deterring China in the Pacific is a clear strategic priority.

But this will not be sufficient to entirely calm nerves among regional allies. As in Europe, there is increasing belief that the US cannot be relied upon as a security partner in the same way as before.

Asia-Pacific countries are confronted by a deteriorating regional security environment, with China rapidly building up its military while cooperating with Russia and North Korea. And potential conflict flashpoints are clearly identifiable, from Taiwan to the Korean Peninsula and in the South China Sea. Defence budgets are expanding as a result.  

Even major collaborative projects, like Australia’s AUKUS nuclear submarine programme, are receiving fresh scrutiny.

Japan, for example, is in the process of massively boosting its historically low levels of defence spending. South Korea is aiming for a 3.6 per cent rise in defence budget in 2025. And Australia’s new national defence strategy calls for an uplift in spending to 2.3 per cent of GDP by 2033-34.    

Meanwhile the Trump administration has called on Taiwan to spend 10 per cent of its GDP on defence, a figure Taipei says it cannot afford.

As in Europe, a large amount of this spending will have been predicated on purchasing US defence equipment. But the unpredictability in US trade and tariff policy may force a rethink. Already even major collaborative projects, like Australia’s AUKUS nuclear submarine programme, are receiving fresh scrutiny following the tariff turbulence of the past few weeks.

Opportunities for others

Doubts about the US will create new opportunities for other rising defence exporters such as South Korea, which in recent years has become one of the top ten arms exporters in the world. Other nations, notably France and Germany, will also be increasingly attractive defence partners and suppliers, even if none can compete with the US’s industry for scale.

Rivals and enemies of the US will be keen to exploit the turmoil, although it is unclear how successful they will be. Russia has lost some of its traditional defence market share as the war in Ukraine has dragged on. Its influence as a security partner has also reduced, as evidenced by its direct loss of security involvement in Syria and in Armenia in recent years.

But China has been gifted a rhetorical victory by Trump’s tariffs: Beijing has long portrayed the US as a selfish and unreliable economic and security partner. The chaotic, aggressive measures announced by the US over the last few weeks seem to have validated that assessment. 

China could spot opportunities to bolster its defence partnerships and supplier relationships, especially in South Asia and in Southeast Asia. Xi Jinping will make his first overseas visits of the year this week to Vietnam, Malaysia and Cambodia to discuss economic relations.

Decoupling

In previous years, the term ‘decoupling’ was associated with Washington’s attempts to encourage its industries and those of its allies to diversify trading dependencies away from China.  

The effect of Trump’s tariff policies has been that in some circles, US allies are now being encouraged to decouple from their security reliance on Washington.

There is now a strengthened rationale for increased security collaboration between mid-sized US partners that circumvents or minimizes US dependencies.

Trump may succeed in forcing US allies to increase their defence spending – but at what cost? There is now a strengthened rationale for increased security collaboration between mid-sized US partners that circumvents or minimizes US dependencies, undermining US leverage. Purchases of US weapons systems may well decline in kind, as rival defence exporting nations grow in strength. Neither effect is likely a desired outcome for Trump.

However the strategic outlook develops over the coming years, countries in Europe and Asia will probably never make the same assumptions about the US’s role in their security arrangements again, even if they remain full participants in their alliances and partnerships with the US.