The US has proposed imposing a huge 220% import tariff on the C-Series jet made by Bombardier (BBC).
The wings of the C-Series are made in Belfast, with around 1,000 jobs linked to their manufacture, according to reports. Production of the wings impacts on 15 smaller aerospace firms and many more that supply components for the wings.
The UK government said it was disappointed in the US ruling. Next February looks to be crucial in the story - that is when the US International Trade Commission will rule on the proposed 220% tariff.
There's more on the story at BBC News.