The formal announcement Thursday that Canada will refuse any further participation in the controversial U.S. missile-defence shield was met with an immediate warning that Canada had given up its sovereignty.
Although Prime Minister Paul Martin said Canada would "insist" on maintaining control of its airspace, U.S. ambassador Paul Cellucci warned that Washington would not be constrained.
"We will deploy. We will defend North America," he said.
"We simply cannot understand why Canada would in effect give up its sovereignty - its seat at the table - to decide what to do about a missile that might be coming towards Canada."
Foreign Affairs Minister Pierre Pettigrew made the Canadian decision public after months of equivocating by the Liberal government and days of denials that a decision had been made.
"After careful consideration of the issue, we have decided that Canada will not participate in the U.S. ballistic missile defence system," Mr. Pettigrew said in the chamber of the House of Commons.
He insisted that the decision - which has reportedly left the Bush administration nonplussed - will not "in any way" hurt ties with the United States.
"We will carefully examine all options and pursue our priorities vigorously," he said.
The announcement came only days after Frank McKenna, the next ambassador to the United States, set off a political storm by saying that Canada is already participating in the missile shield. He said that an amendment to NORAD, the continental joint air-defence pact, meant that Canada's de facto participation had begun.
Mr. McKenna made his comments on Tuesday, about the time, Mr. Martin has now acknowledged, that the United States received the formal refusal from Canada.
"The official Canadian position was conveyed by Foreign Minister Pettigrew to Secretary of State Condoleezza Rice at our meetings in Brussels," he told reporters.
"Since then, I have discussed it with ambassador Cellucci, Mr. Graham has discussed it with [Deputy Defence Secretary Paul]Wolfowitz in the United States and I would expect to be discussing it again, with President Bush, hopefully today or in the very near future."
Mr. Martin's timeline contradicts comments from government MPs this week in the House of Commons, where opposition politicians were told that they would be informed "when a decision is made."
On both Tuesday and Wednesday, Defence Minister Bill Graham insisted that nothing had changed on the missile-defence file and that a decision was forthcoming.
The minority Liberals could have lost if missile defence had come to a vote in the House of Commons. A number of senior government sources have recently told reporters in The Globe and Mail's Ottawa bureau that the federal government felt that the deep unpopularity of missile defence among Canadians made further participation a non-starter.
Mr. Pettigrew said that Canada will continue to contribute to the security of the continent through the expanded mandate of NORAD, the joint continental defence pact that will track incoming missiles, and an integrated response to maritime threats
"We will enhance the protection of North America," he said. "...We will work closely to build the success of [border agreements]and engage Mexico to trilateralize, to better align our roles, priorities and interests."
Mr. Martin said in his comments, moments later, that the Liberal's military priorities are "the ones that we set out yesterday" in the budget, primarily borders, Arctic sovereignty, coastal defence, intelligence-gathering and increasing the size of the army.
With a report from Canadian Press
Oliver Moore