Aerospace giant Bombardier has won out in the trade dispute with rival company Boeing that threatened thousands of jobs in Northern Ireland.
A final ruling on plans by the US commerce department to impose duties of nearly 300% on imports of Bombardier C Series jets was delivered on Friday.
American company Boeing had argued that UK and Canadian government subsidies had given Canadian company Bombardier an unfair advantage in a highly competitive market.
The wings for the C Series are made in Northern Ireland, where Bombardier employs over 4,000 people.
The union Unite had warned of serious rick to local jobs if extra duty badly affected sales.
However, four commissioners from the US International Trade Commission rejected Boeing’s injury claims and unanimously voted to overturn the decision.
Bombardier hailed the ruling as “a victory for innovation, competition, and the rule of law”.
A company statement added: “It is also a victory for US airlines and the US traveling public.
“The C Series is the most innovative and efficient new aircraft in a generation.
"Its development and production represent thousands of jobs in the United States, Canada, and the United Kingdom.
“We are extremely proud of our employees, investors and suppliers who have worked together to bring this remarkable aircraft to the market.”
Unite has also said workers are jubilant at the victory.
Susan Fitzgerald, regional officer for the union’s membership at Bombardier in Northern Ireland, said: “It was workers who walked the halls of Westminster seeking politicians support, or speaking before parliamentary scrutiny committees raising their awareness.
“It was workers who relentlessly travelled to Brussels, Montreal and Washington to make the case; workers who took the campaign to every council in Northern Ireland and who mobilised in their thousands.
“Workers and their trade unions reached out across continents to find common cause despite the corporate dispute ranging above their heads.”
She added: “While celebrating this victory, we must take nothing for granted.
“This decision must now be enforced - Bombardier itself now must reiterate its commitment to the Northern Ireland workforce and end the out-sourcing of jobs to low-cost centres.”