UK finance minister Philip Hammond said Britain would continue to lobby the US over a trade dispute with Canadian planemaker Bombardier, but said there were limits to what it could achieve.
The US slapped a preliminary 220% tariff on Bombardier's CSeries jets, whose wings are made at a plant in Belfast, last week following a complaint from Boeing.
"We've lobbied the US government hard on this issue, but in the end this is a quasi-judicial decision where a citizen or a company makes a complaint and a government department adjudicates it," Mr Hammond said.
"We will go on talking to the US government and the Canadian government in order to protect the jobs at Bombardier in Belfast," he added.
"We have a very, very special relationship with the US but of course every country, the UK, the US, others, all have our own internal domestic processes, our own legal systems and we can't necessarily always ensure that they work in a way that we would like," the UK finance minister stated.