Strains are rising between Canada's contentious provinces and the federal government in Ottawa. Two months ago Prime Minister Pierre Trudeau introduced an energy program that included new taxes on oil and gas. The immediate reaction of Alberta, the principal oil and gas producer, was to impose reductions in the flow of oil to Canada's industrial east. The purpose was to force the east into greater reliance on imported oil, and push the federal energy plan into intolerable deficits. Now another province, British Columbia, declares that it intends to withhold payment of the federal tax on its gas production.

A year ago, the great threat to Canadian unity appeared to be the campaign for a separate and sovereign Quebec, the culmination of a long quarrel revolving around language rights. When Quebec's voters last spring decided against separatism, most people -- at least, most Americans -- assumed that the question of the country's structure was finally settled. But that, it turns out, was premature.

Behind all of this pulling and hauling lies the impending revision of the Canadian constitution. Earlier this year Mr. Trudeau tried to negotiate an agreed text with the provincial premiers. But, like all previous efforts, the talks collapsed over the division of powers. Mr. Trudeau, whose virtues do not include great patience, is fed up with the provincial governments. He is going to proceed, over their vehement objections, to push the new constitution through Parliament, which he and his Liberal Party control.

In the United States, presidents have managed to draw greater power to the national government only in times of those crises that required a national response. Mr. Trudeau is trying to do it in Canada in a period when the current seems to be running the other way, toward stronger regionalism. The only crisis in Canada is the one generated by this constitutional struggle, but it has become interwoven in everything else that Canadian public policy undertakes.

For Americans, the sensible thing is to stay totally out of it. And they need to recognize that transactions appearing down here to be normal business may well appear up there to imply political partisanship. In particular, the bargaining over American imports of gas and oil from Alberta promises a special risk unless it is conducted with great tact and skill on both -- or, as Albertans would say, on all three -- sides of the table.