The North Atlantic Treaty Organization (NATO) has issued many statements declaring the alliance’s opposition to the Treaty on the Prohibition of Nuclear Weapons (TPNW), also called the nuclear ban treaty. Yet despite this public opposition, several key NATO states – Belgium, Germany, the Netherlands and Norway, as well as prospective members Finland and Sweden – joined the nuclear ban treaty’s first meeting of states parties as observers last week. These states maintain that they will not join the treaty, but their positive engagement with the treaty despite strong opposition from NATO’s nuclear powers is a key sign that NATO’s nuclear consensus is more complex than it appears.
The nuclear ban treaty, which is the first comprehensive international prohibition of nuclear weapons, rejects any form of reliance on nuclear weapons for security. Proponents of the treaty argue that nuclear weapons, like other weapons of mass destruction, can never be legitimate tools of war. Though the treaty has been boycotted by the nine states that possess nuclear weapons, including the United States, it still aims to constrain these states by stigmatizing the possession of nuclear weapons and strengthening global norms against their use.
The TPNW meeting of states parties took place in Vienna, against the backdrop of the war in Ukraine. Perhaps no single person has done more to transform NATO than Vladimir Putin. His war in Ukraine has refocused the alliance around the shared security threat of an aggressive Russia. Member states have demonstrated a renewed political and military commitment to NATO, and Finland and Sweden – long partners of NATO but proud of their independence – have submitted applications to join the alliance.
One of the top concerns of Europeans about the ongoing war in Ukraine is the threat that Russia will use nuclear weapons. But even though NATO members share a clear sense of the dangers of Putin’s nuclear threats, there are long-standing tensions among NATO members about how best to manage those risks. Since it was founded, NATO has always relied on the threat of using nuclear weapons for its own security. In response to Russia’s recent aggression, NATO leaders have emphasized the importance of NATO’s deterrent — which includes both conventional and nuclear capabilities. According to the theory of deterrence, leaders like Putin will not use their own nuclear weapons if their adversaries can respond with sufficient force.
However, within NATO, there are many who believe only nuclear disarmament can permanently eliminate the risks of nuclear war. Even if the consequences of nuclear war are unthinkable, nuclear weapons are governed by complex systems that carry the risk of use by mistake or miscalculation. Worse, with the rise of national populism, leaders of nuclear states may be willing to take more extreme risks with nuclear weapons to pursue their goals. These leaders may not be interested in preventing a nuclear war, as demonstrated by Putin’s willingness to use his nuclear arsenal as a tool of coercion.
There are many mainstream political parties and influential domestic constituencies within NATO that are skeptical of the theory of deterrence and want to see urgent action towards disarmament. As traditional arms control and nonproliferation efforts have stagnated, sometimes for decades, anti-nuclear forces within NATO have organized around the nuclear ban treaty as an avenue towards nuclear disarmament.
The United States and NATO’s other nuclear powers, the United Kingdom and France, fiercely opposed the nuclear ban treaty, which makes no exception for NATO’s use of nuclear weapons or nuclear threats. The United States urged NATO allies to boycott negotiations for the ban treaty (all but the Netherlands did); held a press conference outside of the United Nations denouncing the treaty; and, in 2020, urged all states to withdraw their support from the treaty before it entered force. The United States has argued that the nuclear ban treaty is fundamentally incompatible with NATO because it would not permit members to participate in NATO’s nuclear operations and planning.
In reality, NATO already operates its nuclear deterrent without the full participation of all members. Many members have opted out of participation in activities that remain deeply unpopular to anti-nuclear constituencies. Today, Denmark, Norway, and Spain do not permit nuclear weapons to be deployed on their territory during peacetime; Iceland and Lithuania do not permit nuclear weapons to be deployed on their territory at all, even in the case of war; and Iceland, Denmark and Norway forbid port visits from nuclear-armed naval vessels. These policies demonstrate the power of long-standing anti-nuclear sentiment to shape security policy within the alliance.
Until now, NATO’s nuclear powers have managed to hold the line against the nuclear ban treaty through their stiff opposition. Yet, even as support for NATO climbs following Russia’s invasion of Ukraine, it might not be enough to shield allied governments from public pressure on nuclear weapons issues. As the salience of nuclear issues rises in political debate, public views on those issues will have more influence on policy.
The decision of NATO partners to observe the nuclear ban treaty’s first conference is not a sign that these states do not value NATO or alliance unity; rather, it should be understood that influential political forces within these states have serious intentions to pursue pathways to nuclear disarmament. The United States has neglected its leadership on arms control, nonproliferation, and disarmament. This is a clear security concern for several critical US allies.
Instead of trying to enforce a rigid and increasingly fragile consensus on NATO’s nuclear policies, the United States must accept that a coalition of democracies will have diverse security needs and threat perceptions. To maintain political cohesion in NATO will require the US security community to treat nuclear arms control, nonproliferation and disarmament as key security issues, rather than dismiss them as indulgent dreams for peaceful times. The United States must do more to demonstrate to skeptical allies that it can be trusted to act with restraint when it comes to nuclear weapons; that it shares their vision of ultimate nuclear disarmament; and that it can still be a leader even when pathways to a world free of nuclear weapons seem most difficult to find.