Quebec Premier Philippe Couillard came out swinging following the U.S. government's decision to impose sky-high tariffs on the Bombardier CSeries, accusing Canada's largest trading partner of trying to "eliminate a competitor that makes better products."

"Boeing may have won a battle but let me tell you the war is far from over — and we shall win," Couillard said at a news conference Wednesday, in which he called for a united front among the province's political parties. 

"We're going to continue to make this remarkable plane. We're going to continue to sell it all over the world."

Tuesday's decision sent shockwaves through Quebec, with the province's two main opposition parties, the Parti Québécois and Coalition Avenir Québec, calling for an emergency debate today at the National Assembly.

Montreal-based Bombardier and the federal government also slammed the ruling, which has stock watchers bracing for a drop in the company's shares. 

The investigation was sparked by a complaint from U.S. aerospace giant Boeing, after Bombardier secured a deal last year to sell up to 125 of its CS100s to Delta Air Lines.

Tariffs would triple cost of CS100s

In a preliminary decision, the U.S. Department of Commerce ruled that Bombardier benefited from improper government subsidies, slapping duties of nearly 220 per cent, effectively tripling the cost of the jets.

''The U.S. values its relationships with Canada, but even our closest allies must play by the rules," said U.S. Commerce Secretary Wilbur Ross. 

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The U.S. investigation was sparked by a complaint from aerospace giant Boeing, after Bombardier secured a deal last year for up to 125 of its CSeries jets with Delta Air Lines. (Francois Mori/Canadian Press)

Couillard disagreed with the decision, saying the $1 billion US invested by the province in the CSeries program was not a subsidy and that no other investment in Bombardier was currently planned.

Calling the jets the "best planes in the world," Couillard said the issue has nothing to do with subsidies.

"We [were] hit because a giant, itself created, fed by decades of government support in the U.S., has decided to eliminate a competitor that makes better products. It's as simple as that."

Steep duty 'disconnected from reality'

Olivier Marcil, Bombardier's vice-president of external relations, said the duty was "completely disconnected from reality."

​"Boeing did not compete against Bombardier in the Delta deal," Marcil said. "It's not like they finished number two on a deal — they were not even on the playing field."

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Workers assembled at a Bombardier plant in Toronto last week amid calls for Boeing to drop its trade complaint against Bombardier. (Chris Young/Canadian Press)

Prime Minister Justin Trudeau has promised to continue to stand with Bombardier — and threatened to cut government ties with Boeing.

"Obviously, we are disappointed by the decision and I will continue to fight hard for good Canadian jobs," he said Wednesday.

Couillard said he asked Trudeau to make sure that "not a bolt, not a part, of course, not a plane from Boeing" enters Canada until the conflict is resolved, he said.

Boeing 'not attacking Canada'

Boeing, in fact, has a substantial presence in Canada, employing about 2,000 people, according to company spokesperson Dan Curran. Curran said Boeing represents 14 per cent of the Canadian aerospace industry and contributes about $4 billion annually to the Canadian economy.

"Boeing is not suing or attacking Canada," said Curran in an emailed statement. "This is a commercial dispute with Bombardier, which has sold its C Series airplane in the United States at absurdly low prices, made possible by a major injection of public funds, in violation of U.S. and global trade laws."

"We like competition.... And Bombardier can sell its airecraft anywhere in the world," he said. "But competition and sales must respect globally accepted trade law."

The decision faces multiple hurdles before going into effect. Bombardier has numerous avenues to appeal, including the U.S. Court of International Trade, NAFTA and the WTO.

Part of Trump's pledge to 'make America great again'?

David Baskin, president at Baskin Wealth Management in Toronto, told CBC Montreal's Daybreak "Bombardier is not on a level playing field in the United States." 

"Boeing has home court advantage. Donald Trump wants to make America great again. His commerce secretary, Wilbur Ross, a billionaire in his own right, is on his side, and that's what happened yesterday," Baskin said, adding that the stock could take a substantial hit as a result of the ruling. 

"It's a cliché to say that stock markets hate uncertainty, but there's a lot of truth in it, and right now there's a tremendous amount of uncertainty regarding Bombardier."

Air Force One Boeing

U.S. President Donald Trump visited a Boeing assembly plant in South Carolina earlier this year. The head of Bombardier's machinists union believes the 'dice were loaded' in favour of Boeing with regards to the Bombardier ruling. (Mic Smith/Associated Press)

The head of Bombardier's machinists union, for his part, charged that the "dice were loaded" in favour of Boeing.

"We knew ahead of time that we were not necessarily going to get a favourable decision. It's a temporary decision until the case is heard before the courts, but we never expected 220 percent," David Chartrand said. 

"This could dramatically slow things down."

With files from Kamila Hinkson, CBC Montreal's Daybreak and The Canadian Press