The EU customs union is at the centre of Europe’s response after USA President Donald Trump threatened new tariffs against selected European countries in the dispute over Greenland. While the White House is signalling it wants to pressure individual governments, EU trade rules mean member states cannot negotiate or retaliate on their own—and any countermeasure would be designed and applied at EU level.
Why the EU customs union blocks national tariff diplomacy
The EU is a customs union, meaning it is one customs territory for goods.
In practice, this has three consequences that matter immediately in a tariff showdown:
- No customs duties inside the EU. Goods circulate between member states without internal customs checks.
- A single external border and a common tariff policy. Imports entering the EU face a common external tariff set at EU level.
- Trade policy is an exclusive EU competence. Member states cannot run parallel trade diplomacy with third countries. The European Commission, the EU executive, negotiates on behalf of the bloc and proposes trade countermeasures that must apply across the single market.
This is why, even if Trump’s political messaging tries to split the EU by naming specific capitals, the formal response cannot be “Denmark vs USA” or “Finland vs USA”. It is “EU vs USA” — by design.
Can the USA legally single out Denmark or Finland?
Trump can announce tariffs targeting particular European governments, but making them stick in a legally defensible way is another matter.
Under the World Trade Organization’s most-favoured-nation (MFN) principle, WTO members are generally expected to apply the same tariff treatment to “like products” coming from different trading partners, unless a recognised exception applies. In other words, discriminatory tariff treatment between partners in the same legal position is hard to square with WTO rules.
That does not mean Washington lacks options. There are established pathways that can end up hitting one member state harder than others:
- Product-by-product design. A tariff list can be drawn to concentrate pain on sectors strongly associated with one member state (for example, a specific food product, a national flagship industry, or a narrow supply chain). The measure is “EU-wide” on paper, but politically “national” in impact.
- Trade-defence tools. Anti-dumping and anti-subsidy duties are targeted and sector-specific. They require investigations and legal findings, but they can single out a product flow.
- National security claims. Recent years have seen wider use of “security” justifications in trade. This area is legally contested, and it typically raises the risk of retaliation rather than settling the dispute.
The key point for European decision-makers is that the legal and institutional battlefield is collective: if the EU challenges a discriminatory tariff at the WTO or responds with countermeasures, the process runs through EU institutions.
The EU’s countermeasures are collective, and they can go beyond tariffs
European officials and lawmakers are signalling that the EU has multiple “cards” available, but most of them come with costs on both sides.
According to Yle’s analysis, one immediate pressure point could be freezing the ratification of a trade arrangement discussed in 2025, keeping EU tariffs on selected USA products in place rather than moving to “zero tariff” treatment.
Beyond tariffs, the EU’s leverage includes measures that affect how USA companies operate inside the single market, such as:
- Targeted counter-tariffs on politically sensitive USA exports.
- Restrictions in public procurement, potentially including parts of the defence market.
- Tighter controls on exports in strategically relevant sectors.
- Digital-market levers that affect large USA tech firms operating in Europe, from taxation debates to stricter enforcement and fines.
- Data-transfer constraints, which could increase costs for cloud services, advertising and AI development.
A further tool in the background is the EU’s anti-coercion instrument, a legal framework created specifically to deter and respond when a third country uses trade or investment pressure to influence EU or member-state decisions. The instrument is designed to keep the response centralised and scalable — exactly the opposite of the “divide and pressure” logic that tariff threats aim to create.
Trade diversification is part of the same message
Tariff brinkmanship rarely stays confined to customs duties. It also becomes a test of whether a bloc can reduce dependency and keep alternative channels open.
This week, the EU and Mercosur countries signed a long-negotiated trade agreement in Asunción. Whatever the ratification battles ahead, the timing sends a political signal: Europe is looking for new trade partners and leverage outside the transatlantic relationship.
Yle notes that more than three quarters of EU exports already go to destinations other than the USA, which gives Brussels room to argue that it can absorb shocks — although the impact would still be uneven across sectors and regions.
