US Ambassador to Canada Paul Cellucci has warned Canadians that the United States will have no qualms about launching interceptor missiles into Canadian airspace as part of its Ballistic Missile Defense System (BMDS), claiming that Canada "[gave] up its sovereignty"  when it decided not to participate in the program. Cellucci is referring to Canada's right to decide whether the United States is allowed to launch a missile interceptor over Canadian airspace.
Prime Minister Martin, showing a rare display of integrity after over a year of flirting with missile defence, responded to Cellucci's chide about Canada giving up its sovereignty by stating that Canada "would expect and insist on being consulted on any intrusion into our space." 
By contrast, opposition Conservative Party leader Stephen Harper made a typically servile, grovelling response, bewailing the fact that Canada continues to defy Washington. "This will really poison any ability [Martin] has to move Canada-U.S. relations forward. What it means in practical terms is that we'll just be invisible in Washington." 
Of course, the idea that America would ever respect Canada's - or any other nation's - sovereignty is absurd. As the world's predominant superpower, America does what it wants, where it wants, basing its decisions entirely on how the government decides its interests can best be served.
Foreign Minister Pierre Pettigrew asserted this essential fact when he asked, rhetorically, "Would it have been otherwise?" if Canada had decided to take what Cellucci called "its seat at the table". 
Even if Canada was helping to finance BMDS, the ultimate decision on when and where to launch missiles would fall to the United States. It is foolish to believe the US government would ever relinquish control over its own defences.
This is what makes Cellucci's remarks so galling. He came right out and told Canada that it can retain its "sovereignty" only to the extent that it does what America wants it to do. Or as Linda McQuaig cleverly observes, "It's only rape if you resist." 
It's a foregone conclusion that the Stephen Harpers of the Canadian establishment will attach themselves to Cellucci's line of reasoning and use it as an excuse to blame Martin for damaging relations with America, but this decision, like Prime Minister Jean Chretien's decision to stay out of the Iraq invasion, will look better and better as time goes on.
The Associated Press wrote of Martin's decision that "he bowed to pressures to protect his weak minority government and follow the majority of Canadians who have condemned the missile defense program as a rehash of Ronald Reagan's Star Wars."  (Aside: since when is following the majority of your citizens "bow[ing] to pressures"? I thought that was called "democracy".)
Paul Martin and the Liberal Party cabinet have generally supported joining the BMDS, and Martin promised during his last election campaign to improve relations with the United States after they were strained by Canada's decision not to join the US-led invasion of Iraq. Martin bowed out only because, in a multi-party minority government, he is more constrained by what Canadians actually want than he wouuld be with a majority.
This must be frustrating to Cellucci, who hoped that Canada would be willing to fulfill his vision of an "independent but complementary" ally - i.e. willing to serve America's interests in areas where "there's a lot of resentment around the world towards the United States."  As Cellucci explained, "To the extent that Canada has a foreign policy that's independent but complementary to the U.S. and is perceived to be the best friend of the U.S. - that will enhance the role of Canada in the world." 
Not likely. I can only assume Cellucci actually hopes Canada's "independent" support for US policies will enhance the role of the United States in the world. If anything, Canada itself is more likely to suffer from being perceived as an American lapdog than America is likely to benefit from whatever moral prestige attaches to Canada's endorsement of its policies.
Endnotes Alexander Panetta, "U.S. says it would fire missiles over Canada", The London Free Press, February 25, 2005, http://www.canoe.ca/NewsStand/LondonFreePress/News/2005/02/25/941692-sun.html
Susan Delacourt, "No regrets on missile decision, PMO says", The Toronto Star, March 2, 2005, http://www.thestar.com/NASApp/cs/ContentServer?pagename=thestar/Layout/Article_Type1&c=Article&cid=1109717416455
Linda McQauig, "Standing up to US will gain us respect abroad", Rabble, February 28, 2005, http://www.rabble.ca/columnists_full.shtml?x=37552
"U.S.-Canadian Relations Suffer Setback", CBS New York, March 2, 2005, http://cbsnewyork.com/topstories/topstories_story_061082706.html
Beth Gorham, "Cellucci has vision for Canada's foreign policy", Canoe Cnews, February 5, 2005, http://cnews.canoe.ca/CNEWS/Canada/2005/02/05/921730-cp.html
Alexander Panetta, "U.S. says it would fire missiles over Canada", The London Free Press, February 25, 2005, http://www.canoe.ca/NewsStand/LondonFreePress/News/2005/02/25/941692-sun.html
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