On Tuesday, the US Department of Commerce imposed a 219.63 per cent duty on Bombardier's CSeries jets in a preliminary finding, following a complaint by Boeing accusing the Canadian firm of receiving unfair state subsidies.
The decision is a victory for Chicago-based aviation giant Boeing, which said Bombardier used the subsidies to sell its C Series jets at artificially low prices.
Britain is already involved in the world's largest trade dispute, involving mutual claims of illegal aircraft subsidies between Europe and the United States.
"The U.S. values its relationships with Canada, but even our closest allies must play by the rules", Commerce Secretary Wilbur Ross said.
"I think the Department of Commerce and Boeing have not exactly endeared themselves with a rational and sensible approach here".
"Certainly we won't deal with a company that's attacking us and attacking thousands of Canadian jobs", Trudeau said outside the House of Commons. - Delta Air Lines statement.
Bombardier Inc. plunged the most in nearly two years after the US levied import duties on the Canadian company's priciest jet, rattling some of Washington's closest allies and aggravating a trade dispute.
On Wednesday, the U.K. Defence Secretary Michael Fallon made similar comments but stopped short of canceling existing orders with Boeing, although he hinted that future contracts could be at risk.
Allie Renison, head of European Union and trade policy for the Institute of Directors, told the Telegraph newspaper that it's "unhelpful news at the moment given the U.S.is meant to be our first port of call for trade".
Trudeau warned a halt to business with Boeing last week while meeting with British Prime Minister Theresa May in Ottawa.More news: Coroner: 'We don't know' what caused Otto Warmbier's brain damage
British and Canadian leaders have said the dispute would damage Boeing's chances to win defense contracts with their respective governments.
"We don't want to do that".
It's been suggested that Bombardier's move into larger aircraft has anxious Boeing about a nascent competitor that it is now trying to squash at birth.
"After Brexit we'll have to make decisions and be the subject of decisions including from the USA on tariffs and we'd have to work out how we'd respond", she said according to the paper.
United Kingdom involvement: Arguing the tariff undermines Britain's relationship with Boeing, British Prime Minister Theresa May has blasted "protectionism creeping in around the world" despite it being one of the world's "failed ideologies", per the Guardian.
Earlier this year, the Canadian government said it would give Bombardier 372.5 million Canadian dollars (about 299 million USA dollars) in interest-free loans to support its aircraft projects over the next four years.
"The subsidization of goods by foreign governments is something that the Trump Administration takes very seriously, and we will continue to evaluate and verify the accuracy of this preliminary determination", he said.
"Boeing may have won a battle but let me tell you, the war is far from over and that we shall win", he said in Quebec City.
"At the end of the day, as often happens in this type of dispute, the Canadian side will win", he told The Canadian Press in NY.