Canada had more than a front row seat at the dawn of the nuclear age. As part of the Manhattan Project, this country was a player in the bombings that destroyed Hiroshima and Nagasaki 64 years ago this week, providing both uranium and extensive scientific support for the first nuclear weapons. Yet right after the Second World War, Canada made a firm and lasting decision never to pursue the bomb for itself. And so began the nuclear ambivalence that still characterizes Canadian policy.

Canada's nuclear abstinence was in no small measure born out of confidence in, or resignation to, the inescapable reality that it would be a permanent tenant in the widening geopolitical territory under the then-emerging American nuclear umbrella. And from the start it was clear that space under that nuclear umbrella was never going to be rent-free.

Early on, the U.S. Strategic Air Command began using its base at Goose Bay, Labrador, for elements of its strategic bomber fleet. The DEW line, the Distant Early Warning line of radars, was soon installed across Canada's north to warn of approaching Soviet bombers, and Canadian fighter/interceptor aircraft joined their American counterparts to stand ready to defend against any attack.

By dint of geography and an accommodating demeanor, Canada had become a strategic forefield in the MAD (mutually assured destruction) dynamics of the Cold War while at the same time earning a reputation as a stalwart nuclear disarmament advocate. It thus fell to successive governments in Ottawa to balance accommodation to America's nuclear-centric security strategy with a commitment to the disarmament then being urged by the Canadian public and by a concerned international community.

The duality that Canada lived—that is, complicity in the nuclear weapons buildup joined with an active commitment to the elimination of the same weapons—was deeply imbedded within the United Nations itself. From the UN's earliest days, the two leading permanent members of the Security Council were engaged in an intense nuclear weapons competition. At the same time, the first-ever resolution in the UN General Assembly, with the support of the nuclear powers, established a "Commission to deal with the problems raised by the discovery of atomic energy," and directed it to "make specific proposals for the elimination from national armaments of atomic weapons and all other weapons adaptable to mass destruction."

This nuclear contradiction was of course keenly felt as an immediate political conundrum by prime ministers John Diefenbaker and Lester Pearson in the early 1960s. Diefenbaker chose as his foreign minister an ardent disarmament advocate, Howard Green, at the very time he was inviting the United States to install Bomarc missiles in Canada—missiles with only one function, and that was to carry nuclear warheads into the paths of Soviet nuclear bombers transiting Canada en route to targets in the United States. He never did authorize installation of the warheads; that was left for the Nobel peace laureate Pearson, who had earlier opposed the move.

And that is why some 250-450 nuclear weapons were deployed with Canadian forces in Canada and Europe when Canada joined the NPT in 1968 as a non-nuclear weapon state pledging never to acquire nuclear weapons. Canada's arsenal was numerically larger than is China's arsenal today, and larger than the combined arsenals of India, Israel, North Korea, and Pakistan, the only states not party to the NPT.

Pearson's agreement to deploy U.S. nuclear weapons with Canadian Forces earned him the rebuke of the one who succeeded him, Pierre Trudeau, but it was not long before Trudeau too would become possessed of the same nuclear ambivalence. He went to the UN General Assembly's first special session on disarmament in 1978 to present his plan to suffocate the nuclear arms race, a key element of which was his proposed ban on the flight testing of new strategic delivery vehicles. Just five years later he agreed to the flight testing of the U.S. air-launched strategic cruise missile in Canada.

By the early 1980s, Canada had divested itself of all nuclear weapons, but Canada's direct participation in nuclear deterrence and planning operations continued and remains through its membership in NATO and NORAD.

To be sure, most Canadian governments and officials have not regarded life under the American nuclear umbrella as contradictory to disarmament advocacy. Canada saw, and still sees, itself as contributing to nuclear deterrence while it is needed, and at the same time supporting disarmament toward the day when it will no longer be needed.

But 1945 and 1968 have become 2009, and today nuclear deterrence does not so much await disarmament as it actively prevents it. The most compelling nuclear certainty now is that the continued reliance by some on nuclear weapons increases the danger of their spread and ultimate use by either a state or a non-state group. This growing danger is now acknowledged by one-time Cold Warriors like Henry Kissinger and Richard Burt, by current political leaders like Gordon Brown and, especially, Barack Obama, and by figures of extraordinary international stature like Mikhail Gorbachev and current and former UN secretaries-general Ban Ki-Moon and Kofi Annan.

So given Canada's ongoing engagement with the nuclear strategies of NATO and NORAD, what would an end to Canadian nuclear ambivalence look like?

Withdrawal is not really an option—geography militates against us vacating the U.S. nuclear umbrella, and when it comes to the Americans, so does our accommodating demeanor. Besides, the objective is not just to somehow sever Canada's links to nuclear weapons; it is to dismantle the umbrella itself, en route to what Kissinger, Obama, and others see as a world without nuclear weapons.

Ending nuclear ambivalence fundamentally means rejecting the double standard that nuclear weapons are OK for some, but not for others—an unsustainable formula of which NATO is still a pre-eminent purveyor. Challenging the claim that nuclear weapons are "essential" for the security of NATO states, as paragraph 46 of the Alliance's Strategic Concept puts it, is thus central to challenging Canada's nuclear ambivalence.

Another challenge to the double-standard embedded in nuclear ambivalence should come through Canada's nuclear dealings with India. As a condition of selling uranium to India to fuel its non-military nuclear power plants, Canada should insist not only that India ratify the Comprehensive Nuclear Test Ban Treaty, but also that India offer credible assurances that it has joined the five officially recognized nuclear weapon states in halting all production of fissile material for weapons purposes.

As we commemorate Hiroshima Day on Aug. 6, sixty-four years after the bombing of the Japanese city, an extraordinary array of former and current world leaders has finally joined a concerned civil society and an attentive arms control community to insist that in order to prevent the further spread and use of nuclear weapons they must be banned for all. In other words, there is no longer any room for ambivalence on the matter.

Ernie Regehr is co-founder of Project Ploughshares, adjunct associate professor in Peace Studies at Conrad Grebel University College, and a fellow of The Centre for International Governance Innovation.

The opinions expressed in this article/multimedia are those of the author(s) and do not necessarily reflect the views of CIGI or its Board of Directors.