The United States is threatening an increase in tariffs on European Union’s goods, after the World Trade Organization rejected the EU’s claim that it no longer subsidizes European plane maker Airbus.

The WTO ruled on 2 December, that the EU failed to “take appropriate steps to remove the adverse effects” of subsidies on the US.

The corporate dispute in which the EU and the US accuse each other of improperly subsidizing their biggest plane makers Airbus and Boeing, respectively, has lasted since 2006. The WTO has found that both the EU and the US were giving improper subsidies.

The US won on 2 October the right to impose tariffs on $7.5 billion worth of EU imports in its case against Airbus. A trade representative for the US said that EU’s support for Airbus does serious damage to the US aerospace industry.

The European Commission accused the WTO of “serious legal errors” in the case, and is considering appealing.