The European Union (EU) has accused the US of giving Boeing almost $24bn (£12.2bn) in state aid.
In the latest round of a long row over aircraft subsidies, the EU said this had hurt sales of Airbus planes.
The claim came in written evidence to a World Trade Organisation (WTO) panel probing the EU's complaint against Washington DC.
The transatlantic dispute over illegal aircraft assistance is the biggest to come before the global arbiter.
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