At the Non-Proliferation Treaty Review Conference (NPT-RevCon) in January 2022, states parties must find a positive way to deal with a new pillar of the global nuclear architecture: the Treaty on the Prohibition of Nuclear Weapons (TPNW). Bridges must be built to secure the overall stability and thus strengthen disarmament and arms control. The umbrella states in particular should demonstrate their engineering skills in this regard and mediate between nuclear weapon states and TPNW states.
The NPT Review Conference (NPT-RevCon) will bring together delegates and experts from 191 states parties at UN headquarters in New York from Jan. 4–28, 2022. Due to the pandemic, the major get-together of the nuclear arms control community has been postponed three times and will be significantly smaller than in the past. Nevertheless, the 10th NPT-RevCon, which is being held under the Argentine chairmanship of Gustavo Zlauvinen, is a major diplomatic event, not only because seven years have passed since the last one. With the Treaty on the Prohibition of Nuclear Weapons (TPNW), concluded in 2017 and entering into force in 2021, many non-nuclear weapon states (NNWS) are presenting a proposal on how a nuclear weapon-free world could be achieved. The majority of TPNW states parties attach high importance to a prosperous interaction between the two treaties – a fact that is reflected in the preamble and verification provisions, which refer positively to the non-proliferation regime. There is consensus that the NPT has largely prevented nuclear proliferation and therefore remains indispensable.
The Regulatory Conflict and the Umbrella States
Opinions diverge significantly, however, on the duration for which the possession of nuclear weapons is enshrined in the NPT and for how long the distinction between nuclear-weapon states (NWS) and NNWS as two groups endowed with different rights and obligations should be valid. Prior to the indefinite extension of the NPT in 1995, this regulatory conflict could not simply be suppressed. By threatening to let the treaty expire, the NNWS had leverage under international law to remind the five NWS recognized in the NPT. With the TPNW, they have gained a new tool for this purpose. Unlike most of the other NNWS, the umbrella states have so far sided with the NWS on this issue.
NNWS also include so-called umbrella states. They do not possess nuclear weapons themselves, but are covered by the nuclear umbrella of an NWS. The latter’s threat to use nuclear weapons in certain cases (nuclear deterrence) also covers their territory. In addition to NATO countries, Japan, Australia, and South Korea are under the U.S. nuclear umbrella. NATO also includes states where U.S. nuclear weapons are stationed, such as Germany (nuclear weapons hosting states).
Now that the TPNW has entered into force, bridges must be built to maintain the statics of the global nuclear architecture. Constructive responses to the regulatory demands of the NNWS are necessary to stabilize the non-proliferation regime in the long term and to promote disarmament. Withdrawals from the NPT, non-compliance, or lack of participation in resolving regional proliferation crises can thus be countered from the outset.
No other group of states is better placed to do this than the umbrella states. With their renunciation of their own nuclear weapons and in their capacity as nuclear allies, they stand between the NPT-NWS and TPNW-NNWS in the nuclear order. They enjoy the confidence of three NWS and share important security interests with them. At the same time, they consider themselves NNWS and are subject to the International Atomic Energy Agency’s (IAEA) verification regime like all others. Moreover, Germany and many other umbrella states are strong supporters of nuclear disarmament and would be among the first to be affected by a nuclear escalation of geopolitical conflicts. It is therefore precisely in their interest to promote a positive dynamic between the two regimes. The new German government has recognized this and intends to seek observer status at the 2022 TPNW meeting of states. But what can it do to ensure that this does not just become symbolic politics?
Hardly any progress can be made in sub-strategic disarmament relevant for Germany and other umbrella states if everything revolves around capabilities (nuclear hardware) instead of the design of doctrines and operational scenarios (nuclear software). For it is the latter on which depends what capabilities are needed in the first place, i.e. whether, where and to what extent what kind of warheads with what delivery systems should be deployed.
Since the change of administration with President Biden, the U.S. has been revising its nuclear doctrine (Nuclear Posture). The plan is to reduce the role of nuclear weapons and possible deployment scenarios to a minimum (Sole Purpose). Except in the case of an imminent threat of nuclear use by an adversary, first use is to be dispensed with. A nuclear first strike in response to a conventional attack or against a NNWS would thus be ruled out. Such a waiver of escalation options would significantly reduce the risk of nuclear clashes in the sub-strategic area and thus nuclear proxy wars. Since these are among the most likely scenarios of nuclear conflict escalation, a doctrinal adjustment in the direction of Sole Purpose would be a milestone in nuclear risk minimization.
However, the last German Federal Government, together with the NWS Great Britain and France and the two umbrella states Japan and Australia, resisted such a revision vis-à-vis the U.S. Department of Defense as well as within NATO. In doing so, Germany’s Federal Ministry of Defense thwarted the Foreign Office’s efforts in the Stockholm Group (which includes both umbrella states and NNWS) to minimize risk and send positive signals to the NPT-RevCon.
A strong commitment by Germany and other umbrella states to Sole Purpose deterrence would not only be an important contribution to a successful NPT-RevCon. Adaptation would open up substantial new (sub-strategic) disarmament potential and thus create a basis for the withdrawal of nuclear weapons from Germany. All umbrella states would benefit from the associated minimization of nuclear risks, especially NATO states hosting U.S. nuclear weapons on their soil. In order to offer the Central and Eastern European states, which are particularly threatened by Russia’s geopolitical and armament policies, an alternative and more reliable reassurance, NATO would have to significantly upgrade its conventional defense capabilities there. The Federal Republic of Germany, as presumably the largest security policy beneficiary, should make a corresponding contribution to this.
Negative Security Guarantees
Extensive renunciation of nuclear first use would also enable NWS and umbrella states to provide comprehensive negative security guarantees (NSGs) in the sense of a legally binding declaration of non-aggression for members of nuclear weapon free zones (NWFZs) and TPNW states. The NPT-NWS have already made several individual NSG commitments to NWFZs, but the corresponding additional protocols have not always been ratified.
Through the TPNW, many states from nuclear weapon free zones and other NNWS form a global nuclear weapon-free network. Therefore, the TPNW should be treated itself just like a NWFZ. Negative security guarantees for TPNW members that are also members of the NPT would help the TPNW become the backup of the non-proliferation regime (dual membership is rewarded). Withdrawal from the non-proliferation regime would not be attractive even to TPNW members critical of the NPT. In turn, the TPNW would be strengthened as an association of nuclear weapon free zones: It could be referred to by numerous actors and also joined by states that do not yet belong to any NWFZ. In Europe, which as a whole will not become a nuclear weapon free zone in the medium term, alliance-neutral NNWS could join a global NWFZ network with additional safeguards against nuclear weapons use (NSGs). This is a win-win for European security. Umbrella states should therefore advocate such NSGs in their own alliances. The NPT and TPNW would thus be integrated into an overall nuclear architecture that better balances obligations and benefits of the renunciation of nuclear weapons and consequently is more stable.
The umbrella states also share responsibility for fulfilling Art. VI of the NPT, which commits to complete nuclear disarmament. Currently, Art. VI is particularly undermined by NWS modernization programs. Both the United States and Russia are developing new warheads and delivery systems, and China and the United Kingdom are even expanding their arsenals. The umbrella states, which are particularly affected by the U.S. technological update in the sub-strategic area, should therefore advocate a modernization moratorium. Germany could flank and push this initiative within the Stockholm Group, in which it plays a leading role. To prove its own credibility, Berlin should also refrain for the time being from agreeing to any new investments and procurements that explicitly or exclusively serve the maintenance and further development of nuclear sharing.
Impetus for Multilateralization
Moreover, the multilateralization of disarmament verification, which was cautiously initiated in the TPNW, must also be advanced within the NPT regime. Existing bilateral disarmament and arms control agreements are reaching their limits and are not adequate to the new geopolitical realities. The P5 format offers the greatest prospects for success in multilateralizing the nuclear arms control architecture, provided that it is embedded in the NPT review process and fed back to NNWS.
In contrast, constellations of three (Russia, the U.S., China) outside the NPT framework and without France and the United Kingdom, are difficult for Beijing to accept because U.S. allies have similarly large nuclear arsenals. The umbrella states should therefore promote a two-level approach of the P5 to their nuclear allies. This might include as a basis a joint moratorium on modernization and freeze of stockpiles by all P5 and convergence of nuclear doctrines towards minimum deterrence. At the same time, Russia and the U.S. would have to further reduce their arsenals to approach the level of the other NWS. It is furthermore important to actively engage NNWS in verification.
Germany’s engagement with the U.S., Norway, the U.K., and France in researching and testing verification methods involving NNWS must be translated into practical policy. Involving NNWS in verification is, not least, a key to building confidence to engage NWS such as China (and India and Pakistan in the future) in nuclear arms control, countries that are skeptical of Russia and the U.S. because of the latter’s experience advantage in this area. At the NPT-RevCon, such initial ideas should be introduced and fed into the next round of the review process.
In its coalition agreement, the new German government expresses its willingness to cooperate as an observer at the first Meeting of States Parties to the TPNW and its desire to make the NPT-RevCon 2022 a “real impetus” for nuclear disarmament. For both conferences to become bridgeheads for a better link between disarmament and non-proliferation, umbrella states and their nuclear allies must do their part to dovetail the two treaties. With concrete commitments to reduced deterrence (Sole Purpose), negative security assurances, moratoria, and multilateralization initiatives, viable foundations for a stable bridge could be laid.
 Russia, the U.S., China, France and the United Kingdom.
 Only a Russian nuclear attack could trigger this scenario in Europe, for example. In the Asia-Pacific region, it would be theoretically impossible, at least in the conflict with the U.S., because of China’s renunciation of first strike.
 Financial Times (2021-10-30), Demetri Sevastopulo, Henry Foy, “Allies lobby Biden to prevent shift to “no first use” of nuclear arms.
 The proposals indicate the direction in which multilateralization initiatives could go. Existing multilateral 2nd track projects such as the Arms Control Academy ACONA are possible starting points and could be used and expanded to build confidence. In the multilateralization of verification, the dialog platform CEND (Creating the Environment for Nuclear Disarmament) initiated by the U.S., in which Germany also plays a major role, could serve as a connection point. It could be further developed and include a corresponding working group.
IAEA – International Atomic Energy Agency
NNWS – Non-Nuclear Weapon States
NPT – Non-Proliferation Treaty
NPT-NWS – Nuclear Weapon States that are signatories to the NPT
NPT-RevCon – Review Conference of the Non-Proliferation Treaty (NPT Review Conference)
NSG – Negative Security Guarantees
NWFZ – Nuclear Weapons Free Zone
NWS – Nuclear Weapon States
P5 – Permanent Five (China, France, Russia, the United Kingdom and the United States); group of permanent members of the United Nations Security Council
TPNW – Treaty on the Prohibition of Nuclear Weapons.
TPNW-NNWS – Non-nuclear Weapon States that are signatories to the TPNW.