The European Union on Tuesday (October 13) won the right to impose retaliatory tariffs on U.S. goods.
The World Trade Organization ruled the EU can charge levies worth $4 billion on imports from the U.S.
That's in retaliation for subsidies granted to planemaker Boeing by the U.S.
It's a decision that could further inflame transatlantic trade tensions, with just three week to go until the U.S. Presidential election.
Although optimists will hope it could settle a 16-year legal battle over subsidies given to their respective planemakers - Boeing and Airbus.
Tuesday's decision follows a ruling last year that allowed Washington to impose tariffs of $7.5 billion on EU goods over state support for Europe's Airbus.
But there have been signs both sides are willing to negotiate a resolution.
The state of Washington has moved to repeal tax breaks that were of benefit to Boeing.
In turn, Airbus has announced it will increase repayments on loans granted to help develop its A350 planes.
For now though, while the European Commission has said it would prefer a negotiated solution, it can move ahead with tariffs.
It has a long list of U.S. products to target, including wine, spirits, tractors and a range of agricultural produce.
Combined, the two cases represent the world's largest ever corporate trade dispute.