It's a landmark day for nuclear disarmament, but an awkward one for the federal government

This column is an opinion by Setsuko Thurlow and Bianca Mugyenyi. Thurlow, the co-recipient of the 2017 Nobel Peace Prize on behalf of ICAN and recipient of the Order of Canada, survived the bombing of Hiroshima and has devoted her life to nuclear abolition. Mugyenyi is a director at the Canadian Foreign Policy Institute. For more information about CBC's Opinion section, please see the FAQ.

Today is an extraordinary day for humanity. Yet it is an awkward moment for Canada.

At midnight the Treaty on the Prohibition of Nuclear Weapons (TPNW) entered into force. For the 51 countries that have already ratified it, developing and possessing nuclear weapons is now illegal. The treaty requires ratifying nations to, "never under any circumstances … develop, test, produce, manufacture, otherwise acquire, possess or stockpile nuclear weapons or other nuclear explosive devices."

Beyond making weapons that have always been immoral now also illegal for nations that have joined the treaty, it requires signatories to promote nuclear abolition. Similar to the landmine and cluster-bomb treaties, the TPNW seeks to stigmatize the stockpiling and use of nuclear weapons in the hopes of changing the behaviour of all nations, including non-signatories.

The pressure is not only directed at the state level. It is also aimed at companies, universities and other institutions that enable nuclear weapons development, research and production.

Yet despite stating that it is committed to nuclear disarmament, Canada's federal government has refused to sign the TPNW.

Nuclear weapons continue to pose a serious threat to human survival. There have been accidents involving these weapons in the U.S., Spain, Russia, British Columbia and elsewhere over decades. Similarly, early warning system failures have almost led to drastic decisions by the leaders of nuclear armed states.

Tens of millions could die instantaneously if nuclear weapons were exploded over cities. The use of a fraction of the more than 13,000 nukes in the world could imperil billions in a global famine and through radioactive fallout.

The UN Institute for Disarmament Research, as well as the Bulletin of the Atomic Scientists, argue that the risk of nuclear weapons use is at its highest in decades.

Nuclear armed Israel, Pakistan and India have never signed the Nuclear Non-proliferation Treaty, while North Korea withdrew and is building up its arsenal. In recent years the U.S. has pulled out of the Intermediate-range Nuclear Forces (INF) treaty, Iran nuclear deal and Open Skies Treaty. Washington is spending $1.7 trillion over three decades to modernize its nuclear stockpile with new bombs that are 80 times more powerful than those it dropped on Hiroshima and Nagasaki. By positioning troops on Russia's doorstep, including Canadians in Latvia, the NATO alliance is heightening tension between the two great nuclear armed powers.

Amidst the dangers of a nuclear conflict, the TPNW is a bright light. In 2017, 122 countries voted in favour of the treaty's adoption at the United Nations.

Canada, however, has been hostile to the initiative. It voted against establishing talks for the treaty and then boycotted the negotiations, which two-thirds of all countries attended. More recently, Canada voted against a December UN resolution supporting the TPNW, a resolution backed by 130 UN member states.

Meanwhile, Global Affairs has claimed in recent months to "unequivocally support global nuclear disarmament" and a "world free of nuclear weapons."

Just two weeks ago during a meeting of foreign ministers of the Stockholm Initiative for Nuclear Disarmament, Parliamentary Secretary to the Minister of Foreign Affairs Rob Oliphant reiterated in a government statement that, "Canada is committed to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) and its part in achieving a safer and more peaceful world. Now is the time to make a concerted effort, working with like-minded partners, to advance our shared nuclear non-proliferation and disarmament objectives. We are committed to achieving a world free of nuclear weapons."

So why is the Trudeau government refusing to sign the TPNW prohibiting nuclear weapons?

Initially Prime Minister Trudeau dismissed the UN conference that negotiated the treaty, stating, "there can be all sorts of people talking about nuclear disarmament, but if they do not actually have nuclear arms, it is sort of useless."

As support for the TPNW has solidified, the government's tone softened. It now asserts that it prefers to focus on the Non-Proliferation Treaty (NPT), which opened for signatures in 1968.

However, signing the TPNW is not at odds with seeking to reinvigorate NPT negotiations.

Ottawa's opposition to the prohibition treaty appears driven by the military and political establishment's ties to the United States and NATO (the Liberal government's defence policy makes two dozen references to Canada's commitment to NATO).

In a bid to block the treaty that went into effect today from reaching its ratification threshold, Washington sent a message in late October urging countries, including Canada, to "withdraw your instrument of ratification or accession" to the TPNW.

The nuclear-armed NATO alliance is also hostile to the treaty – in December, the alliance reaffirmed its opposition to the TPNW.

While the Liberals may not be on board, the NDP, Greens and Bloc Québécois have all expressed support for Canada signing the TPNW.

Additionally, former prime ministers Jean Chrétien and John Turner, former deputy prime minister John Manley, former defence ministers John McCallum and Jean-Jacques Blais, and former foreign ministers Bill Graham and Lloyd Axworthy all signed an international statement in September supporting the UN Treaty on the Prohibition of Nuclear Weapons.

If the federal government adopted their vision to prohibit nuclear arms, many in Canada would proudly celebrate.

• This column is part of CBC's Opinion section. For more information about this section, please read our FAQ.