Generally speaking, Canada-U.S. relations rely on the premise that we, in Canada, recognize the Americans' strategic priorities. One of the fundamental elements of Canada-U.S. relations is that Washington determines what constitutes a threat, not Ottawa. Usually, we have to adapt to how Washington defines the threat.
Where Canada has some flexibility is in how it confronts that threat. Canada has always exercised that flexibility. We can't prevent the U.S. from taking action to defend North America, but we can negotiate the terms and conditions of our role in that defence.
As long as Canadians assert their desire to contribute to North America's security, they will have the Americans' respect. The Americans aren't really inclined to infringe on Canada's sovereignty as long as Canada asserts its responsibilities.