President Trump’s announced intention to impose import tariffs of 25% on steel and 10% on aluminium touched off a wave of retaliation threats and trade policy responses from trading partners, including the EU. This column examines the scope for retaliation against the Trump administration’s proposed tariffs under WTO dispute settlement. It estimates that if the sources of all US steel and aluminium imports were part of this dispute, trading partners would be permitted to retaliate by a collective amount of $14.2 billion per year.