Commentary: South Korea braces for a tougher Trump on trade and US military protection

BUSAN: President Donald Trump last week singled out South Korea as an example of countries taking advantage of the United States, warning of higher tariffs and signalling that he may push for Seoul to pay more for US forces stationed there.

“China’s average tariff on our products is twice what we charge them. And South Korea’s average tariff is four times higher … And we give so much help militarily and in so many other ways to South Korea,” Mr Trump said during his speech to Congress.

The US-South Korea relationship is characterised by two things Mr Trump dislikes in US allies: A trade surplus in the ally’s favour, and a costly US defence commitment.

South Korea routinely runs a trade surplus with the US – meaning that it exports more to the US than it imports. In 2024, that surplus was US$66 billion; in 2023, it was US$51 billion. The US also stations 28,500 soldiers and their dependents on a string of bases across the peninsula.

Mr Trump will almost certainly demand that the surplus goes down and the cost for US military protection goes up. In his first term, he made these demands too, threatening to pull US troops if South Korea did not pay US$5 billion under a defence cost-sharing deal.

South Korea baulked at that huge increase (in 2019, South Korea paid US$924 million), hoping that Mr Trump would lose the election in 2020 so that it could negotiate with more internationalist-minded Joe Biden. That approach worked, but the new cost-sharing agreement, in which South Korea has agreed to pay 1.52 trillion won (US$1 billion), does not go into effect until 2026, giving Mr Trump all year to renege on it.

As it is, during his presidential campaign in October, Mr Trump escalated his rhetoric, calling South Korea a “money machine” and saying it should be paying US$10 billion for US troops.  

A NEW REALITY FOR US ALLIES IN ASIA

Mr Trump’s foreign policy approach has already begun to dramatically change America’s alliance structure in Europe. His stance on NATO and his direct engagement with Russia over Ukraine suggest a more transactional view of international partnerships.

Similarly, Mr Trump has long conceived of US overseas troop deployments as mercenary protection for which America should be paid. In his recent negotiations with Ukraine, for example, he framed his suggested US-Ukraine minerals deal as Ukrainian compensation for American aid.

His commentary about US allies in Europe suggests he does not feel compelled by treaty to defend them. If this anti-alliance approach extends to the Indo-Pacific, it will almost certainly ignite a regional arms race between China and the democracies near it.

It might also ignite Japanese-South Korean rivalry, given the substantial tension between these two. And it will likely lead to nuclear proliferation, as US allies doubtful of Mr Trump’s commitment to their security scramble to develop their own deterrent to China.

South Korea will probably be the first country in the region to feel renewed pressure. Japan is America’s most important regional partner, so Mr Trump will probably proceed cautiously with Tokyo. But South Korea is a smallish ally of middling importance to the US, so it may find itself under greater scrutiny.

As Mr Trump ramps up pressure on US allies, they all face the question of placating him with concessions, or drifting away from the US toward a more independent foreign policy line. In Europe, the latter option is hard. European defence spending is so low that the continent’s military capabilities and defence production capacity have atrophied. This has been Mr Trump’s core leverage over Ukrainian President Volodymyr Zelenskyy in their recent tension. Europe is unable to replace American support for Ukraine, which Mr Zelenskyy knows.

South Korea, in contrast, does have the capability to go its own way. Its defence spending is twice the European average. Its military is large because of conscription and it has an excellent defence industrial base. It can mass-produce shells, tanks, missiles, and so on. Should it come under pressure from the US, South Korea would be better placed to break with the Americans than Europe is.

AN EAST ASIAN ARMS RACE

This would likely occur slowly. South Korea is in a tough neighbourhood, so it will want to avoid the open breach witnessed between Mr Trump and Mr Zelenskyy in the White House recently. It will likely try to flatter Mr Trump first, as it did with moderate success in his first term.

But there are limits, as we see in Canada’s increasingly fierce rejection of Mr Trump’s tariffs. And in South Korea’s case, greater foreign policy independence would almost certainly mean its development of nuclear weapons. South Korean public and elite opinion have been tilting pro-nuclear for years now, and Mr Trump’s recent actions have re-energised that debate.

Should the US Indo-Pacific alliance network fragment, expect other countries to consider big defence budgets and nuclear weapons too.

Without firm US support, Australia and Japan may reassess their non-nuclear status, while Taiwan might expand its military capabilities to bolster its defences against China. South Korea and Japan may even fall into rivalry.

The US-South Korea alliance has endured for more than seven decades. Seoul will have to tread carefully.