The US Commerce Department has added to Canadian plane maker Bombardier's problems with the announcement of a further import duty on its CSeries aircraft.
The Canadian firm, which employs 4,000 people in Belfast, has been slapped with a second preliminary levy of 80% on the exports of its planes to the USA, the Trump administration announced on Friday.
The wings for the new aircraft, which are due to be delivered to the United States next year, are made at Bombardier's plant in the DUP stronghold of East Belfast.
The new duty follows a preliminary finding that Bombardier sold 75 CSeries jets below cost to Delta Air Lines Inc (DAL.N) in 2016.
A spokesperson for Bombardier said: "We strongly disagree with the commerce department's preliminary decision".
The U.S. said a final decision on the Boeing complaint is slated for December 19.
Montreal-based Bombardier said in a statement that the Commerce Department's decision was an "egregious overreach" and "misapplication" of trade law that is created to "block the CSeries aircraft from entering the USA market".
The Commerce Department proposed a 79.82 percent antidumping duty on Friday, on top of a 219.63 percent duty for subsidies announced last week.
The penalties were imposed after officials decided Bombardier got illegal help from the United Kingdom and Canadian governments.
"The United States is committed to free, fair and reciprocal trade with Canada, but this is not our idea of a properly functioning trading relationship", Ross said.
Last month, the US government approved the sale of 18 Boeing Super Hornet jets to the Canadian military, at a cost of 6.4 billion Canadian dollars (about 5.1 billion USA dollars), to replace Canada's aging fleet of CF-18 Hornets from McDonnell Douglas, which merged with Boeing in 1997.
The key decision likely won't come, however, until the U.S. International Trade Commissions decides whether the Bombardier-Delta deal actually hurt Boeing's business, a decision that's not expected until early February.
Earlier this week, the International Trade Commission bolstered that policy by finding USA washing machine makers have been harmed by rising imports from South Korea.
In a statement on Friday, she said the Canadian government was "extremely disappointed by and in complete disagreement with" the new tariff that "put [s] at risk the nearly 23,000 U.S.jobs that depends on Bombardier and its suppliers".
Canadian Prime Minister Justin Trudeau is scheduled to meet with US President Donald Trump on Wednesday. "We will continue to verify the accuracy of this decision, while doing everything in our power to stand up for American companies and their workers".
Bombardier shares were last up 0.5 percent to C$2.20.
In a separate case, the World Trade Organization last week approved Brazil's request to investigate Canada's alleged use of more than $3 billion in government subsidies to produce Bombardier aircraft.