Boeing, with the support of US regulators, has charged the Canadian government of providing Bombardier with unfair subsidies, which then allegedly allows the company to sell its aircraft in USA markets at below-market prices.
"This hypocrisy is appalling" the spokesperson added, "and it should be deeply troubling to any importer of large, complex, and highly engineered products".
The decision intensifies political pressure on NAFTA negotiators ahead of next week's resumption of talks among Canada, Mexico and the U.S.
The decision is expected to heighten trade tensions that flared last week after the United States announced a preliminary duty of almost 220 percent for subsidies Bombardier received, which was well above the 80 percent duty Boeing sought in its complaint.
U.S. Commerce Secretary Wilbur Ross said in a statement on Friday that "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". "We will continue to verify the accuracy of this decision, while do [ing] everything in our power to stand up for American companies and their workers".
Canadian Foreign Affairs Minister Chrystia Freeland was also sharp in her criticism of the new duty against Montreal-based Bombardier.
Commerce said it based Bombardier's preliminary dumping margin on adverse facts available (AFA), because Bombardier failed to provide the information it requested.
The Bombardier aircraft subject to the investigation have not yet been imported into the US.
The US Department of Commerce ruled against aerospace firm Bombardier in its dispute with rival Boeing.
Now, Commerce has indicated that an anti-dumping penalty of 79.82% should be added to the duty. To achieve that, Boeing will have to prove to ITC it was harmed by Bombardier's sales.
"We will look to the USA to ensure the process is rigorous and not politically influenced", he said.
He said workers will fight even harder to get the duty reversed. "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".
Canada has threatened to cancel the planned purchase of 18 Super Hornets to temporarily augment Canada's aging fleet of CF-18s.