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Your guide to what the 2024 US election means for Washington and the world

Donald Trump prides himself on his unpredictability and transactional approach to life. These are tactics that might work well in the real estate business or a debt restructuring. But when it comes to international politics, Trump’s transactionalism is likely to prove very costly for the US itself as well as for global stability.

One of the great advantages that the US has over China or Russia is that it has a global network of allies, created over the long term. Countries like Japan, Germany, Australia, Canada and Britain have often had doubts about the wisdom of particular US policies. But they have stuck with America because they believed, in the last resort, that their alliances were based on a firm bedrock of shared interests and values.

The tariff war launched by the US — combined with the often hostile language of the Trump administration — has shaken that trust to the core. Mark Carney, the new prime minister of Canada, says that the US is “no longer a reliable partner”. Friedrich Merz, the next chancellor of Germany, has called for Europe to “achieve independence” from America. Anthony Albanese, the Australian prime minister, says the Trump administration’s tariffs on Australia are “not the act of a friend”.

The White House might be inclined to dismiss these kinds of statements as empty emoting. And it is true that many governments, hit by tariffs, may now scramble to do a deal with Trump to try and mitigate the damage to their economies. But they are also likely to make long-term adjustments to their policies — aiming to reduce their vulnerability to American bullying. This, over time, will have long-term consequences for America’s own wealth and power.

There are economic and strategic implications. One obvious impact could be on American arms sales. With the US threatening Greenland, the territory of Denmark, a Nato ally, the drive to “buy European” weaponry is growing within the EU. One of the rationales advanced by Trump for his protectionist agenda is the need to reindustrialise America. But it would be a bold foreign investor who commits to a long-term investment in the US, when tariff policies change frequently and when any increased reliance on America could be seen as potential leverage to be exploited.

Then there’s the geopolitical cost of Trump’s willingness to round on his allies. The president’s entourage seems to believe that America has little strategic stake in the future of Europe, so they may not mind losing the trust of their transatlantic allies.

The Trump administration does, however, seem to be very committed to containing Chinese power in the Indo-Pacific. The Biden administration, which shared that commitment, did a good job in building up America’s network of alliances and friends in the regions. But, Trump’s tariffs are a gut-punch to America’s most important allies in north-east Asia — Japan and South Korea. Shigeru Ishiba, Japan’s prime minister, has called the Trump tariffs a “national crisis” and convened emergency cross-party talks.

The likes of Japan, South Korea and Australia have been prepared to work with the US to contain and manage Chinese power because they believed that, in the last resort, the US would fight to defend them. But Trump’s transactional, unpredictable and increasingly hostile actions are destroying that trust. America’s alliance system will also now come under huge strain — to the benefit of China.

The US president has profoundly changed the Republican party and the image of America itself. In a matter of days he has undone trusted global relationships that have taken decades to build. The task of reviving such trust, even after Trump is no longer in office, will be gargantuan — if it is possible at all.