When one gets past the chauffeurs and the grand residences, leadership can be hard work.

That's why the government of Canada should be commended for standing up to its relentlessly liberal critics in Parliament as well as much of its "street" and announcing on Aug. 5 that it will allow the United States to use data gathered by Canadians at NORAD, the North American Aerospace Defense Command, in the development of our missile defense system.

It's a great deal for Canadians. They merely acknowledge the United States can use NORAD's radars and other devices as the eyes and ears of its missile defense system, and they get the same protection as Americans. To say no would have been foolish; the United States would merely have constructed its own parallel early warning system, and NORAD, which both countries have relied on since 1958 to track airplanes and incoming missiles and provide for our joint defense, would've been essentially moot.

Yet polls say nearly 70 percent of Canadians oppose even this tiny step, even though its government did not commit beyond this step to participate in America's missile defense program. Members of Parliament from nearly every party, including the prime minister's, also oppose Canadian involvement - one argued that it amounted to the "weaponization of space," which Canada officially opposes.

The opposition to participating in missile defense comes down to four points, all of them misguided in today's post-9/11 world:

• The system doesn't work.
• It's not cost-effective.
• Other more-effective, less-expensive options exist.
• Missile defense amounts to a blatant break from détente, the START I and II treaties, and is actually a commitment to a peace-through-force imperative that will only further spur a nuclear arms race. Not to mention that missile defense means taking the fight to space, where Canadians have said they don't want it to go.

First, the system does work, and it's getting better all the time. It has worked perfectly during the last three tests and four of the last five. And this argument is disingenuous anyway, since those making it aren't interested in spending anything to make the system more effective.

Moreover, the United States is constructing a system in Alaska right now. All Canada did was save both countries some money, strengthen a necessary and effective alliance and assure its citizens maximum protection.

Second, today, neither country could stop even one missile lobbed from North Korea or China. And while we probably can count on cooler heads in China to prevent any of its missiles from heading our way, we can't count on any stable decision making in Pyongyang.

The current phase of our program will cost about $5 billion - small change in a budget of more than $400 billion. According to a recent Congressional Budget Office report, it could cost upwards of $80 billion to research, construct and deploy a "boost-phase system" - one that would intercept incoming missiles soon after takeoff so the collision, destruction and fallout from those missiles would occur over enemy territory, not ours.

What is a fair price for security? Most right-thinking people would agree it's a bargain for Americans at $80 billion and an even bigger bargain for Canadians, who would be required to spend far less.

Third, sea-based (such as Aegis cruisers) and other systems (such as the Patriot missiles used by U.S. forces in the Middle East) are effective against shorter-range missiles, but North America is also threatened by long-range missiles. And again, would those who push for "other options" be willing to pay to fix those systems to cover all this ground? Or are they simply raising these objections when they have no intention of supporting what it would take to overcome them?

Fourth, détente and other weapons-control treaties worked to keep the Soviet Union at bay, but Canadians ought to realize that our adversaries today operate on different principles. They don't care whether we retaliate - most are content to die during their attacks on us anyway. They may or may not act on behalf of a state against which we could retaliate.

Despite the best efforts of the United States and others, such as Russia, we no longer can account for all the fissile material in the world. How long until a private person or group, controlled by no nation, obtains enough nuclear weapons and missile technology to threaten the lives of millions of Americans and Canadians? Further, the U.S. is now executing a treaty with Russia that will reduce its deployed strategic nuclear arsenal to its lowest level in decades.

A missile shield will be our only defense. Kudos to Canada's government for recognizing this and getting the country on the right side of history, even if a majority of Canadians don't yet see it that way.

Baker Spring is the F.M. Kirby research fellow in national security policy at The Heritage Foundation.