The EU will impose tariffs on U.S. products in the dispute surrounding aircraft manufacturers Airbus and Boeing, European Commission Vice President Valdis Dombrovskis said on Monday.

A recent World Trade Organisation ruling permitted the EU to impose tariffs, Dombrovskis said.

“And that’s what we are doing,” he said.

The ruling, issued in mid-October, allows the EU to impose tariffs worth nearly four billion dollars (3.37 billion euros) on U.S. imports annually to retaliate against unfair aircraft subsidies.

The EU would remain open to negotiations, however, with the commission advocating for both sides to drop tariffs on each other’s products, Dombrovskis said.

In a similar case, the WTO authorised the U.S. in 2019 to impose tariffs on EU products worth up to 7.5 billion dollars (6.3 billion euros) in response to illegal state aid to European plane-maker Airbus.