Ramesh Thakur is a professor at the Australian National University and co-convenor of the Asia-Pacific Leadership Network for Nuclear Non-Proliferation and Disarmament. Cesar Jaramillo is executive director of Project Ploughshares in Waterloo, Ont.

Negotiations begin Monday at the United Nations in New York on a "legally binding instrument to prohibit nuclear weapons, leading toward their total elimination." These talks flow from resolutions adopted late last year by the General Assembly in landslide votes. These negotiations could be the most significant multilateral development on nuclear-arms control since the indefinite extension of the Non-Proliferation Treaty (NPT) in 1995 and the adoption of the Comprehensive Nuclear Test-Ban Treaty in 1996.

The impetus behind the talks is growing consciousness of nuclear dangers, frustration at the glacial pace of nuclear-disarmament efforts, and exasperation at the nuclear-weapon states' disregard of their legal disarmament obligations. Most of them – and most U.S. allies that shelter under its nuclear umbrella, including Canada and Australia – won't be at the UN talks.

Story continues below advertisement

Last October, Washington called on allies to vote against ban treaty negotiations and not to join ensuing negotiations. States heeding the U.S. request are on the wrong side of history and humanity. Their refusal to participate is flawed on substance and probably in breach of their NPT obligation to promote nuclear disarmament. It is also a self-defeating tactic as they are rejecting the opportunity to influence the debate and shape the text of the eventual treaty.

Read more: Nuclear sabre rattling grows around globe, yet Canada chooses sidelines

Canada's proud record of leadership in nuclear-arms-control initiatives makes its submission to U.S. obstructionism especially egregious.

Nuclear peace depends on deterrence and fail-safe mechanisms working every single time. Nuclear Armageddon will result from deterrence or fail-safe mechanisms breaking down just once. Similarly, stable deterrence requires rational decision-makers in every nuclear-armed country all the time.

Story continues below advertisement

More than 15,000 nuclear warheads continue to threaten Earth. Even a limited nuclear exchange would bring incalculable loss of life to humans, animals, plants and ecosystems. Yet, while every other category of weapon of mass destruction has been specifically prohibited under international law, nuclear weapons have not.

A renewed focus on the humanitarian impact of nuclear weapons has served as both catalyst and rallying point for an ever louder demand for concrete progress toward abolition. Nuclear ban talks fulfill the 2014 Humanitarian Pledge signed by 127 countries "to stigmatize, prohibit and eliminate nuclear weapons."

Revived for a shining moment by former U.S. president Barack Obama in Prague in 2009, the dream of a world free of the threat of nuclear weapons has steadily faded since then. All nine nuclear-armed states are modernizing their nuclear systems. China, India, Pakistan and North Korea are expanding their arsenals. Meanwhile, geopolitical tensions are rising in high-risk theatres involving nuclear powers in Eastern Europe, the Middle East, South Asia, the Korean Peninsula and the South China Sea.

All 191 NPT states have committed to "pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament." In 1996, the World Court advised, unanimously, that "there exists an obligation to pursue in good faith and bring to a conclusion negotiations leading to nuclear disarmament in all its aspects under strict and effective international control." The UN talks conform to this obligation.

Story continues below advertisement

Negotiations signal a recognition that a ban treaty can be useful in creating the structures necessary to support a world free of nuclear weapons. Of course, only nuclear-weapon states can take practical steps to reduce and eliminate these weapons. But a ban treaty will reinforce the boundary between conventional and nuclear weapons, strengthen the norm of non-use of nuclear weapons and make nuclear planning more problematic, and reaffirm non-proliferation and disarmament norms.

The nuclear-weapon policy goals can be summarized as: cap and contain; de-legitimize; reduce; prohibit; and eliminate. Only those possessing nuclear weapons can undertake the first, third and fifth tasks. But non-nuclear-weapon states can pursue the other two goals – stigmatization and prohibition – as an affirmation of global norms. In this way, they exert pressure on possessor states to pursue the other three goals.

Despite the nuclear powers' endless excuses, the international community considers a ban treaty urgent, essential and – absent any arms control negotiations today – the only practical way to achieve real disarmament.