Setsuko Thurlow, a Hiroshima survivor and activist with the International Campaign to Abolish Nuclear Weapons, speaks at Oslo City Hall after ICAN officially received the 2017 Nobel Peace Prize in Oslo. (Terje Bendiksby/NTB scanpix/AP)

On Sunday, the International Campaign to Abolish Nuclear Weapons (ICAN) received the 2017 Nobel Peace Prize in Oslo. ICAN won the prize “for its work to draw attention to the catastrophic humanitarian consequences of any use of nuclear weapons and for its ground-breaking efforts to achieve a treaty-based prohibition of such weapons.” Beatrice Fihn, the executive director of ICAN, accepted the prize along with anti-nuclear activist Setsuko Thurlow, an 85-year-old survivor of the Hiroshima atomic bomb.

But the United States — along the United Kingdom and France — reportedly snubbed the prize winners by sending lower-ranked diplomats instead of ambassadors to the ceremony. The United States and its close allies took a strong stance against the Treaty on the Prohibition of Nuclear Weapons (TPNW) that ICAN helped establish. Adopted by the U.N. General Assembly on July 7, the TPNW prohibits its signatories from possessing, threatening the use of, transferring, testing or stationing nuclear weapons.

Why the strong opposition from the United States? U.S. officials have lobbed a variety of criticisms against the treaty, claiming variously that it will have little effect on disarmament, as no states possessing nuclear weapons plan to join; that it will undermine the Nuclear Non-Proliferation Treaty; and that nuclear reductions through treaties negotiated among the nuclear possessor states are the only feasible path toward disarmament.

But there is a more immediate, although rarely stated, concern: This new treaty could undermine the cohesion of NATO, an explicitly nuclear alliance.

The United States pressured NATO allies to oppose the treaty

In November 2016, before the U.N. General Assembly vote on a resolution to begin negotiations on a nuclear ban treaty, the United States sent an informal diplomatic paper to its NATO allies outlining the ways in which the proposed treaty would undermine the stability of the international system, delegitimize nuclear deterrence, and complicate NATO planning and nuclear burden-sharing. It states, “We strongly encourage you to vote ‘no’ on any vote at the UN First Committee on starting negotiations for a nuclear ban treaty.”

This pressure was successful; no U.S. allies voted in favor of the U.N. resolution, although the Netherlands abstained. In the end, the Netherlands was the only U.S. ally to participate in negotiations, as its legislature required it to do so. U.S. pressure on NATO allies and partners surrounding this treaty continues.

In September, Defense News reported that Defense Secretary Jim Mattis sent a letter to Sweden — a NATO partner — threatening future U.S. military cooperation if Stockholm joins the TPNW.

Should the United States be worried that NATO allies might join the treaty?

Although the United States might still be concerned that its NATO allies might join the treaty in the future, here are three reasons why current trends appear to work in favor of the U.S. position.

1) Most NATO members are putting the alliance first. First, most NATO member governments have spoken out against the treaty, claiming it is at odds with their alliance commitments. One country of particular concern for the United States was Norway. Under its labor coalition government from 2005 to 2013, Norway provided significant funding to ICAN and, in 2013, held the first of three well-attended international conferences on the humanitarian effects of nuclear weapons use. When this government lost the election in 2013 to a conservative coalition, ICAN lost a major source of support. Many in the disarmament community hoped a return of a labor coalition would lead to Oslo’s support of the new treaty. In elections this September, however, the conservative coalition retained power. The Netherlands is another government in which there is some domestic support for the treaty, but its leaders have also declared they would not support it.

2) Russian aggression makes this a tricky time to talk about disarmament. A second factor dampening NATO enthusiasm for the TPNW is Russian aggression, especially since 2014. Annexing Crimea, destabilizing Ukraine, cheating on an arms control treaty, conducting provocative military activities near NATO borders and issuing nuclear threats are all behaviors that have NATO leaders thinking twice about rejecting nuclear weapons.

In interviews I conducted with disarmament advocates at the U.N. negotiations this summer for a forthcoming article, many indicated that Russia’s resurgence meant the treaty’s timing was less than ideal. Indeed, the change within Europe on this issue is well illustrated by German behavior. In 2009 and 2010, Germany and a handful of other NATO states wanted to discuss the removal of U.S. nuclear weapons from Europe. Earlier this year, in contrast, Germany revealed that it had conducted a study on whether it would be legal for the state to fund the British or French deterrent in exchange for protection. Talk of removing U.S. nuclear weapons from Europe has waned significantly, and in 2014 at the Wales Summit and in 2016 at the Warsaw Summit, NATO reaffirmed its role as a “nuclear alliance.”

3) Most people just don’t pay much attention to nuclear weapons policy. A final factor working against adoption of the treaty in NATO states is the continued low salience of nuclear weapons among the general population. The three humanitarian conferences in 2013 and 2014 brought awareness of nuclear weapons effects to a new generation of diplomats and advocates, but to the average citizen, nuclear weapons probably remain Cold War relics. For example, in a poll of Europeans younger than 30 published in 2017 concluded that “this generation is not on the verge of mobilization regarding nuclear weapon issues and does not expect to actively engage in it.” Without significant and widespread domestic pressure to join the treaty, it is unlikely that leaders would risk disrupting relations with their NATO allies.

Polling conducted on behalf of ICAN suggests that when asked about a nuclear ban treaty, many European populations are in favor of it, but polls rarely ask if the participants had heard of the treaty before taking the survey or whether they consider the risk of nuclear weapons in their daily lives. Without some major change or incident putting nuclear weapons at the forefront of the population’s attention — current tensions over North Korea’s nuclear program do not seem sufficient thus far — this appears unlikely to change.

ICAN has done important work in bringing global attention to the effects of nuclear weapons. All leaders should have a clear understanding of the risks involved in maintaining such weapons. It seems doubtful, however, that the new treaty will be splitting the NATO alliance anytime soon, as geopolitical trends are leading to a greater reliance on nuclear weapons and the broader public appears to lack interest in this issue.

Rebecca Davis Gibbons is a visiting assistant professor in the Government and Legal Studies Department at Bowdoin College.