Local politicians and trade union representatives have said they are extremely disappointed Bombardier has been hit with further potential tariffs by the US in a trade dispute.
Bombardier is facing a 300% duty on its exports of planes to the US after the US government proposed adding a further 80% tariff in an international trade dispute.
One of Northern Ireland's largest employers is already facing a planned 220% tariff on its aircraft as part of a separate investigation, the US Department of Commerce confirmed.
US commerce secretary Wilbur Ross said the trading relationship with Canada was not "properly functioning" and they would do "everything in our power" to stand up for American companies.
The Canadian-owned Bombardier employs more than 4,000 people at its Belfast factories and is due to begin delivering an order for up to 125 new jets to Atlanta-based Delta Airlines next year.
The dispute was sparked by complaints from rival Boeing that Bombardier received unfair state subsidies from the UK and Canada, allowing 'dumping', or the export of a product at a lower price.
Bombardier said it strongly disagrees with the Commerce Department’s decision, which “represents an egregious overreach and misapplication of the US trade laws”.
Unions have warned thousands of jobs could be in jeopardy.
Davy Thompson from Unite says the union is confident the preliminary ruling will be overturned but is calling for action from the government.
“In the context of rising protectionism, US authorities appear intent on taking every opportunity to impose punitive tariffs on Bombardier,” he said.
“Institutions such as the International Trade Commission and Department of Commerce which project themselves as guardians of the free market are now proactively closing the US markets by raising protectionist barriers to new and superior market entrants.
“Unite the union’s focus remains with safeguarding the jobs and skills base in Belfast. This ruling places a serious threat to four thousand workers at the five Bombardier sites in Northern Ireland as well as the approximately 20,000 whose jobs are sustained by the stimulus provided by the workers’ wages and the wider procurement associated with the company.”
East Belfast DUP MP Gavin Robinson said the only way for a resolution “is if there’s an agreement between Boeing, Bombardier and the Canadian government”.
“I think what’s most regrettable about last night’s additional tariff is the bullish comments that have been made by Boeing and the US Commerce Secretary.
“So from that perspective we need to redouble our efforts, that’s the British government, Canadian government and Bombardier themselves to scope out the prospects of and securing a resolution to this ongoing dispute.”
He added: “The ramifications for these tariff suggestions, I think go far beyond than Bombardier in this instance, but Bombardier is where our focus must be.”
Alliance East Belfast MLA Chris Lyttle also renewed calls for the UK, US and Canadian Governments to collectively resolve the ongoing trade dispute.
He said the interim rulings ran contrary to the spirit of open competition.
“Bombardier is the cornerstone of the manufacturing sector in Northern Ireland, both as the largest employer and enabler of a wider engineering supply chain. Any permanent negative ruling against it would have a massive impact on many livelihoods and the wider economy," Mr Lyttle said.
“Alliance has already been in contact with the highest reaches of the UK, US and Canadian Governments, and these letters reiterate the need for the Governments to facilitate and broker an outcome to this dispute.
“There remains a short time in which this matter can still fairly resolved and I hope the Governments take the opportunity to ensure an outcome which supports free and open competition, and protects Bombardier’s critical presence in Northern Ireland.”