OTTAWA -- Justin Trudeau came out swinging at the U.S. government Friday over its investigation into a trade dispute between U.S. aerospace giant Boeing and Canadian rival Bombardier.

But the prime minister refused to discuss what other options the Liberal government would have if it were to follow through on its not-so-subtle threat to abandon plans to buy 18 of Boeing's Super Hornet fighter jets.

The Liberals appeared to link the trade dispute and fighter-jet purchase the day before, after U.S. officials in Washington held a hearing into dumping allegations that Boeing brought against Bombardier.

Foreign Affairs Minister Chrystia Freeland released a statement after the hearing saying the government was "reviewing current military procurement that relates to Boeing."

Government officials and industry representatives said the planned Super Hornet purchase was the only ongoing military procurement project with Boeing.

Trudeau didn't mention Boeing or the Super Hornets by name while responding to questions at an event in Surrey, B.C., on Friday, but did have some tough words for the U.S. government.

"We strongly disagree with the actions taken by the U.S. Department of Commerce and we are making that very clearly known," he said.

"We will be respectful and work constructively with the United States, but we will always be resolute and firm in how we stand up for Canadian interests."

The Liberal government has spent six months arguing about the urgent need for more fighter jets to supplement Canada's aging CF-18s, and that the Super Hornets it plans to buy are the only real option.

Trudeau sidestepped questions about what other avenues the government has available if it decides to follow through on its threat to cancel the purchase in retaliation for Boeing's case against Bombardier.

"We know that we have a responsibility to the men and women of the Canadian Forces," he said. "But we're always going to be very thoughtful about standing up for Canadian rights and what is right at the same time."