This week's test of the United States' cruise missile in Canada was also a test for the nation's antinuclear movement and for Pierre Trudeau's Liberal Party.
By failing to stop the test, antinuclear protesters are now posing the same question protests had when they failed to stop the deployment of cruise and Pershing II missiles in Europe last fall: ''Is this a mortal blow?''
''Round One to them,'' answers Jim Stark, leader of the nationwide coalition opposing the test.
The Liberal government, meanwhile, faces a federal election this year, and the cruise test casts a shadow over its prospects.
Significantly, Mr. Trudeau was careful to assure Parliament that Tuesday's test would be the last and only one this year.
Trudeau, who recently wound down his international peace initiative and announced his intention to resign, defended the test.
''Testing the cruise doesn't make Canada a nuclear power,'' he said, ''and we earned credibility as a reliable NATO partner.''
Trudeau's initiative, which earned him a nomination for the Nobel Peace Prize , has widespread support from Canadians. His Liberal Party's popularity increased a few points in the polls from recent record lows; party insiders quietly credit the gains to his peace initiative.
The issue of the cruise test galvanized the country last year. Normally reticent, Canadians took to the streets in unprecedented numbers. But the decision to proceed with the tests was made at Cabinet level. It never reached Parliament for a vote.
The testing agreement with Washington was widely believed to have been part of a tacit deal on assorted bilateral issues and would have been discomfiting to rescind. No one, it seems, was surprised that the test finally took place, but it was announced only 48 hours in advance.
The test began Monday night when a lone green-and-white US Air Force B-52 bomber, carrying four missiles on its wings, took off from a US base in North Dakota. It flew a 1,500-mile corridor over the frozen Northwest Territories, northeastern British Columbia, and then south to Alberta's Primrose Lake air weapons range near Cold Lake Air Force Base.
It returned to the US without touching down in Canada. The cruise guidance system is believed to have performed well.
The flight was followed by protests across Canada. To avoid a blockade by a hundred test opponents, military helicopters ferried journalists and observers 20 miles to view the flight.
In a last-minute decision in Ottawa, a federal court judge refused to issue an injunction to halt the flight.
The political fallout from the test resulted in charges of hypocrisy against Trudeau.
''Many were confused by the mixed signals of Canadian policy, expecting that Trudeau's peace mission meant that cruise testing would be canceled. Logically and morally it should have,'' said Don Erickson, chairman of the National Peace Petition Campaign.
''But this confusion has now vanished and been replaced with resolve. The testing poses a direct challenge none of us are going to ignore.''
''The Liberals have been trying to channel the momentum of the peace movement all along - our efforts last year saw to the launching of Trudeau's peace mission. But they should be careful. This issue is an iceberg - and the Titanic of the political structure is headed straight for it.''
Erickson's group has been organizing for a year in anticipation of an election. It is active in all of Canada's federal electoral districts and has the support of organized labor, the churches, and antinuclear groups.