Since February 2022, Ukraine has been defending itself against yet another Russian war of aggression. Now that immediate support – military, diplomatic, financial and humanitarian – for Ukraine has improved, the country’s long-term security needs to be addressed. Looking ahead, security commitments should be built on political, economic and military pillars. NATO membership is essential for Ukraine’s security, but it is also in the geostrategic and normative interests of the Alliance, even if it is a risky, long-term and difficult endeavour. At the 2023 summit in Vilnius, NATO recognized that Ukraine’s future is in the Alliance but remained vague about the conditions to join. Yet, other agreements announced on the margins of the summit by the G7 and individual states expand the support for Ukraine. Framed as steps to increase Ukraine’s security, these should accompany the transition from current security support to future guarantees.
The renewed Russian invasion since February 2022 has increased the urgency for Ukraine to obtain security guarantees. In March 2022, President Zelensky – under extreme pressure – proposed neutrality for his country and abandoning the goal of joining NATO if Ukraine were to receive security guarantees from the five permanent members of the United Nations Security Council and other partners. However, the discovery of the Russian massacres in Bucha and Irpin, together with Ukraine’s military successes, has rendered this idea obsolete – not least because trust in any security assurances from Russia has evaporated. In September 2022, Zelensky applied for “fast-track” NATO membership instead.
In Western countries, there have been controversial discussions about how Ukraine’s security can be guaranteed. Proposals range from neutrality through bilateral and multilateral security commitments to NATO membership. For example, the Kyiv Security Compact – drafted in September 2022 under the leadership of the head of Ukraine’s presidential administration, Andriy Yermak, and former NATO Secretary-General Anders Rasmussen – outlines detailed proposals for military, economic and political support, with clearly defined consultation and decision-making processes bundled together in a multilateral framework document.
Ukrainian and European interests
From a Ukrainian perspective, reliable security commitments are necessary because previous approaches have failed: neither the Budapest Memorandum (1994) nor the political support of Western states prevented the annexation of Crimea, the destabilization of Donbas from 2014 onwards or the 2022 full-fledged invasion. In line with the Budapest Memorandum, Ukraine handed over all former Soviet nuclear weapons on its territory, in return for which Russia, the UK and the US pledged to respect Ukraine’s sovereignty and territorial integrity. However, no provisions were made for concrete security commitments; there was only the obligation to consult with and refer to the UN Security Council in the event of a conflict. Russia violated the Budapest Memorandum through the annexation of Crimea in 2014, which is why Zelensky demanded in May 2022 that renewed pledges should “not be declarations of intent” but should provide “concrete guarantees”.
The assumption here is that Ukraine’s security and sovereignty would be fragile and contested not only in the event of continued warfare or a ceasefire but even if it were to succeed in liberating all the occupied territories. This is because Russia’s intentions will remain aggressive as long as it challenges Ukraine’s territorial integrity, state sovereignty and national identity – as outlined by President Putin in revisionist essays – and as long as it perceives warfare as a legitimate and efficient means to advance its interests. Moreover, in September 2022, Russia proclaimed the annexation of another four Ukrainian territories (Donetsk, Luhansk, Zaporizhzhia and Kherson). Under the Russian Constitution, they – like Crimea – cannot be returned. This means that conquering and integrating all those territories remain Russian state goals. So, if Russia were to reduce hostilities or announce a ceasefire, it would be not because of Moscow’s having abandoned its maximum objectives but because of a lack of capabilities or for tactical reasons. As long as the Russian leadership continues to cling to its neo-imperial and aggressive approach, an imminent threat remains.
However, it is also in the interests of the members of the European Union (EU) and NATO for Ukraine to be secure and sovereign in the long term. First, a Ukraine occupied in whole or in part by Russia would significantly worsen the security situation in Europe. The deployment of Russian troops on Ukrainian territory, together with the transformation of Belarus into a Russian military outpost, could expand Moscow’s power projection capabilities vis-à-vis the EU and NATO. Russia’s success in Ukraine would serve only to strengthen Moscow’s conviction that foreign policy interests can be achieved efficiently and effectively by military force. The two pillars of the militarization of Russian foreign policy – capabilities and intentions – can be toppled only if Russia suffers a clear defeat and Ukraine’s state sovereignty and territorial integrity are secured in the long term.
Second, military support for Ukraine is already contributing to the defence of the rules-based order in Europe and thus to European security, stability and prosperity. Russian aggression is aimed not just at Ukraine but at reshaping the European security order in its own favour. This is demonstrated in the draft treaties that Moscow presented to the US and NATO in 2021. Here, Russia not only demanded an end to the Alliance’s “open-door policy” but also requested the withdrawal of all troops and weapons that were stationed on the territory of Allies that had joined NATO since 1997. This underscores that Russia aims to establish a buffer zone consisting of NATO’s eastern members and perceives the post-Soviet space as an exclusive zone of interest, where it rejects the full sovereignty of states like Ukraine. Ensuring the security and sovereignty of Ukraine thus also contributes to ensuring the security of EU and NATO members.
Third, the security situation in Europe would be more stable if what is now one of Europe’s strongest and most combat-experienced armies were to be integrated into NATO after the war. Should the Ukrainian armed forces remain outside the Alliance, Europeans would have fewer opportunities to provide gentle guidance for them – and that could have destabilizing consequences.
Fourth, a stable security environment is needed for Ukraine’s reconstruction. In February 2023, the World Bank estimated the cost at US$ 411 billion. Such an enormous effort, which will require both public and private investment, demands a secure framework. If reconstruction were to fail or falter, the security situation could deteriorate and the democratic reform processes slow down.
Finally, Ukraine’s EU accession includes a security dimension. The country was granted candidate status in June 2022. According to Article 42(7) of the EU Treaty, member states are obliged to support one another in the event of an armed attack. Yet, the EU countries are already unable to defend the Union without US capabilities.
Three options for security guarantees
Numerous options offering various degrees of support have been discussed, but most stop short of credible security guarantees. Thus, Ukraine is seen not as an ally that will be defended but as a partner that is to be supported, although the scope, nature and desired end goal of such cooperation vary. Hence, these options are more aptly called “security commitments or assistance”. There are only three that offer Ukraine the maximum, reliable support that could qualify as a guarantee.
The first is the demilitarization of Russia – that is, the reduction of its armed forces and arms industry to a level that would allow it to engage only in self-defence, not offensive operations. This would also entail the demilitarization of its strategic culture. However, such fundamental changes can usually take place only through long-term socialization processes or as a result of external shocks. The latter include a clear defeat by Ukraine and the Russian leadership, together with large swaths of the population, ceasing to view Russia as a neo-imperial power, which would inevitably mean regime change and a critical reappraisal of the country’s hegemonic past. But even then, Ukraine could feel secure only if Russia were to simultaneously denuclearize.
The second option is for Ukraine to strengthen its deterrent potential through unilateral nuclearization – that is, either building up its own nuclear arsenal or applying pressure through the announcement of such a step. After all, nuclear deterrence currently protects both Russia and NATO. Admittedly, acquiring nuclear weapons would be a very complex and protracted undertaking that would have little chance of success without Western support; it would yield security gains only in the long term while at the same time damaging Ukraine’s reputation. Nonetheless, as South Korea demonstrated in March 2023, such an announcement can help obtain US increased security support. If Ukraine were to choose this path, it would move closer to the Israeli model, which is based on strong armed forces, nuclear weapons and bilateral security agreements.
The demilitarization of Russia is unrealistic while the renuclearization of Ukraine is clearly undesirable. Not only would it put a severe strain on the European security order and undermine the global non-proliferation regime; it would almost certainly prompt Russia to escalate the war.
That leaves the third option: Ukraine’s integration into bilateral or multilateral systems of collective defence. A bilateral alliance with US guarantees and / or a network of bilateral alliances with militarily strong states, preferably nuclear powers, could guarantee its security. However, while countries are offering security assistance, they have refrained from providing guarantees that go beyond support to constitute a pledge of mutual defence. The bilateral and minilateral agreements announced within the G7 at the margins of the 2023 NATO summit offer support but not guarantees. This is because no state appears to want to take the risk of a military confrontation with Russia. Given its long-term orientation towards the Indo-Pacific, it is unlikely that the US would commit to guaranteeing Ukraine’s security in this way. For the Europeans, who have a vested interest in the security of Ukraine, it would not be desirable either. Rather, the most effective deterrent against Moscow would be Ukraine’s NATO membership.
Risks and conflicting goals
There is still no consensus within NATO on when and under what conditions Ukraine will be allowed to join. In 2008, the Alliance offered Kyiv the prospect of membership but spelled out neither a clear timeframe nor what the individual steps towards accession would be. This left Ukraine in a security-policy grey zone.
Since 2022, Secretary-General Stoltenberg has emphasized that while Ukraine’s place is in NATO, it can join only once the war has ended.
The lack of consensus among NATO Allies led to the 2023 Vilnius decisions, which intensify cooperation between NATO and Ukraine, promise accession, but do not outline the path to it as clearly as Ukraine and some allies hoped. While some NATO states called for Ukraine’s timely accession and reliable commitments to be agreed at the 2023 summit (Poland and the Baltic states), the US and Germany, in particular, were cautious. And it is these two states that would be politically and militarily pivotal to making any security promise credible. Indeed, Ukraine’s NATO accession entails numerous risks, mainly in relation to four elements: the threat of escalation, timing, territorial scope and NATO’s capacity to act.
(1) NATO allies must weigh the goal of Ukraine’s long-term security against the short-term escalation threat. The latter includes the risk of Russia escalating the war (conventional or nuclear) and / or taking it beyond Ukraine into NATO countries. However, Russia’s possible “red lines” are difficult to read and Moscow is deliberately conceptualizing them in a blurry way. Also, the Russian leadership subsumes national security under regime security. Risks are weighed according to the extent they endanger the stability of the authoritarian system. Since Putin’s third term in office (from 2012 onwards), regime legitimacy has changed – from the promise of economic prosperity to the immaterial sources of legitimacy, which include the demonstration of great powerness to the outside world, the “gathering of Russian lands” and the confrontation with the West. Thus, Ukraine joining NATO would be a significant blow to a keystone of the Kremlin’s legitimacy narrative of Russia’s great powerness and, together with a military defeat, could destabilize the regime. Such a development at home could prompt Putin to further escalate the war.
Moscow’s reactions could range from another round of partial mobilization to full mobilization or even the staging of a nuclear incident; the use of tactical nuclear weapons cannot be ruled out either. Admittedly, there is no evidence to date of any concrete steps towards a massive military escalation beyond Ukraine. Also, in view of the limited military success Russia has had in recent months, it is questionable to what extent it would be able to further escalate. Yet, the escalation threat cannot be ruled out given the possible destabilization of the Putin regime and its non-transparent decision-making processes, which increase the danger of miscalculations.
At the same time, hybrid threats could intensify. The Kremlin could exploit differences within NATO over Ukrainian accession to weaken the unity of the Alliance and thus its ability to act. Moscow could also seek to influence a controversial accession debate by means of disinformation, portraying Ukraine’s accession as escalation in order to stoke Western fears (for example, through nuclear threats) and thereby cause Western support to dwindle. Furthermore, it is conceivable that Russia would use Ukraine’s NATO accession on the international stage to underscore its narrative of a hegemonic West. Deliberately playing with unpredictability is one of Russia’s manipulation mechanisms to destabilize Western societies and institutions. And in 2024 there will be several opportunities as elections are due in many Western countries, including the US and several European states.
(2) Risks are also associated with the timing of Ukraine’s accession to NATO. According to NATO Secretary-General Stoltenberg, Ukrainian membership is possible only after the war, but he has not clarified whether a ceasefire or a peace agreement would be required. While such conditionality reduces the risk of NATO being drawn into the conflict, it could increase the incentive for Russia to continue its aggression in order to prevent Ukraine’s accession to the Alliance, meaning that Moscow would de facto have a veto over Ukraine’s NATO membership.
(3) There is a similar dilemma over which territory NATO security guarantees should apply to. Ukraine does not fulfil one of the 1995 accession criteria: namely, the absence of territorial disputes (the other requirements include a functioning democracy and market economy, the fair treatment of minorities and democratic control over the military). If NATO were to make accession conditional on the resolution of territorial disputes, that could provide another incentive for Russia to ensure the conflict with Ukraine continues to simmer to prevent accession. It would thus be in the Allies’ own interest to allow flexibility in fulfilling this criterion– for instance, by temporarily limiting the geographical areas to which defence commitments apply and drawing up supplementary agreements. History provides examples of potential mechanisms, even if the geopolitical conditions were completely different: West Germany joined NATO in 1955 on condition that it would not pursue German unification unilaterally by military means, otherwise Article 5 would not apply. And while the Soviet-controlled German Democratic Republic was, of course, not a NATO member, the eastern regions of Germany joined the Alliance when Germany united in 1990.
In the case of Ukraine, it is possible to envisage that the free territories would join NATO in addition to the Alliance committing to extend its protection to the occupied territories after their liberation. Ukraine would be subject to mandatory consultations for military operations and Article 5 conditionality in the event of unilateral action. And there would have to be consequences if Ukraine were to violate these conditions.
(4) Yet another risk is that Ukraine’s accession could undermine NATO unity, which is a prerequisite for its ability to act as a defence alliance. The overall accession debate is already putting a strain on NATO. The last stage of Sweden’s accession process was extremely difficult, because Turkey had blocked it for domestic reasons. Some Allies are concerned that Ukraine’s accession could import existing conflicts into NATO, as Kyiv’s relations with some of its neighbours, including Hungary, were difficult before the war and still are today. Others fear that there would be too much focus on Russia at the expense of other threats listed in the 2022 Strategic Concept, such as instability on NATO’s southern flank and China.
Moreover, many Allies are afraid of being drawn into the war – for example, if Russia were to provoke Ukraine along a contact line or border after accession and NATO were forced to react or if Kyiv were to decide unilaterally to liberate territories that had remained occupied after accession. In such cases, decision-making within NATO could lead to divisions, which Russia would know how to exploit. A Russian attack post-accession to which the Alliance responded in a divided manner would signal a failure of NATO and pose a risk for Ukraine.
Clearly, there is a trade-off between the benefits of Ukraine’s long-term integration into Western structures and the short-term risk of weakening the internal cohesion of those very institutions through the ongoing debate, thereby jeopardizing support for Ukraine. Since NATO accession is realistic only in the longer term, tackling related issues could be postponed for now. Not least, Ukrainian success on the battlefield could lead to possible new solutions. Nonetheless, NATO should already be thinking about flexible approaches that allow for the gradual expansion of security commitments.
Militarily, Ukraine’s accession would require adjusting NATO defence plans and structures so that the Allies can defend the new NATO territory and integrate Ukrainian forces into Allied structures and planning. To underscore the credibility of NATO commitments once Ukraine is a member, it would be advisable to station troops there, especially from major states such as Germany and the nuclear powers France, the US and the UK. However, it is Washington and Berlin that are the most sceptical. As long as the US, the key security provider, does not support Ukraine’s NATO membership, it will not happen. Because of the declining US interest in European security, it is, above all, the Europeans who are going to have to make more effort. However, the latter are struggling to implement NATO’s adaptation process launched in 2019. As of 2022, only seven of the 30 Allies had fulfilled the 2014 Defence Investment Pledge – i. e., the obligation to invest 2 per cent of national GDP in defence. At the 2023 Vilnius summit, the Allies agreed that often expenditure beyond 2 per cent of GDP will be needed. While many states are increasing their defence budgets, it is unclear how sustainable these commitments are and at what point they will improve operational capability.
Yet, neither Ukraine nor NATO itself would benefit from a political commitment by the Alliance that was not backed militarily. Rather, it would damage NATO’s credibility and thus Europe’s security and stability. Therefore, accession should take place only if Ukraine meets the conditions or if alternatives have been agreed.
While the Allies clearly declared at the 2023 Vilnius summit that “Ukraine will become a member of NATO”, they did not spell out the next steps. They stated only that they would “extend an invitation to Ukraine (…) when Allies agree and conditions are met”.
Because rapid accession remains unrealistic, intermediate steps are needed to significantly and reliably enhance Ukraine’s security prior to accession.
How to move from security pledges to security guarantees
In Vilnius, NATO Allies framed the latest measures in support of Ukraine – the new NATO-Ukraine Council (NUC), the additional cooperation programmes and the dropping of the requirement for a Membership Action Plan (MAP) – as a path to membership. Several other agreements concluded on the margins of the Vilnius summit complement these NATO decisions. Particularly important is the G7 Joint Declaration of Support for Ukraine, which outlines military, financial and economic support for Kyiv while demanding that the necessary domestic reforms be undertaken. It is framed as a roadmap for Ukraine’s “integration into the Euro-Atlantic community”. Given the crucial importance of the outcome of the war for European security, it is essential to clearly frame these measures as a path to NATO accession, not as a substitute.
At the same time, to avoid any misunderstanding on the way to accession, NATO must clarify that Article 5 provisions will not apply until membership. Nevertheless, the Vilnius measures and those outlined below will offer added value compared with mere ad hoc support as long as they are based on a long-term logic (rather than being ad hoc) and focused on a specific goal (Ukraine’s security and NATO membership). This will require binding commitments, consultation and decision-making processes, which, in turn, will mitigate the frictions caused by ad hoc measures.
In order to ensure Ukraine’s security on the path to NATO membership, a comprehensive and interconnected approach is needed – one that protects the country in a more effective and scalable way. In fact, the military, political and economic components of such an approach are both mutually dependent and reinforcing: a secure framework is a prerequisite for economic reconstruction, and it is the latter that enables investment in security. Thus, mutually reinforcing measures involving various actors (EU, NATO, G7, the Ukraine Defense Contact Group), such as those agreed in Vilnius, are essential. The aim is to anchor Ukraine once and for all in Euro-Atlantic structures and to make clear to both Kyiv and Moscow as well as to EU and NATO states that Ukraine belongs to those structures and is not a buffer or grey zone. The focus here is on the security policy pillar.
The security policy pillar
Security commitments should define the path to security guarantees, i.e., NATO membership. The aim is to strengthen Ukraine and improve its security in such a way that the country would be ready for accession when the political opportunity arose, i. e., when Allies agree and conditions are met, as stated in Vilnius. As a result of the Vilnius decisions taken by NATO, the G7 and individual states, a comprehensive support programme has been launched. To be successful, implementation should focus on three elements: strengthening Ukraine’s self-defence capability and further anchoring it within NATO; weakening Russia’s military capabilities; and boosting the resilience, deterrence and defence of EU and NATO.
(1) The Vilnius agreements are crucial, but implementation should ensure that they serve as a bridge to NATO membership, not as a substitute for it. NATO should follow the agreed path, step up its cooperation with Ukraine and the individual Allies should implement the bilateral and minilateral agreements that are already in place or have been announced. The focus should be on long-term systematic support to enable Ukraine to end the conflict on its own terms.
In Vilnius, member states agreed to expand existing cooperation and to underpin them with a multiyear funding scheme in order to showcase the Alliance’s long-term commitment to Ukraine. It must be made clear to Russia that Western support is permanent and that Moscow’s playing for time will not work. What should still be improved is the intensification and long-term financing of arms deliveries (including ammunition, maintenance, logistics and replacement of destroyed equipment), training programmes (bilateral, EU and NATO), investments in and cooperation with the Ukrainian arms industry, technology partnerships and increased intelligence cooperation.
So far, lethal support for Ukraine has deliberately been provided outside NATO structures via the Ramstein Format and on a bilateral basis to prevent any direct involvement of the Alliance in the war. This policy was continued in Vilnius. At the same time, military support in non-lethal areas, such as demining, is being stepped up.
For their part, the G7 countries announced that they would “work with Ukraine on specific, bilateral, long-term security commitments and arrangements” in three areas: defence and deterrence, economic stability and resilience, and technical and financial support. They committed to, inter alia, equipping Ukraine with modern armaments, modernizing its defence industry and increasing intelligence cooperation. Furthermore, EU, NATO and G7 states launched bilateral and minilateral agreements that are a key complement to the NATO pillar – for example, the F16 coalition, which will support Ukraine by delivering Western jets and training pilots. Moreover, the commitments received by Sweden and Finland between application and accession and those proposed in the Kyiv Security Compact could serve as a blueprint for Ukraine’s accession path. Anchoring Ukraine in regional European formats, such as the UK led Joint Expeditionary Force (JEF), would further signal its integration into the Western alliance.
Beyond that, the Allies should support Ukraine’s politico-military integration into NATO by every means that is below the threshold of Article 5. Here, the Vilnius decisions are a step forward: the new NUC gives Kyiv more tools to engage with NATO. However, this should not be a one-way street; the Allies should also use the NUC to learn from Ukraine, for example its combat experience. Meanwhile, the Alliance could invite Kyiv to selected meetings of the North Atlantic Council.
Post-Vilnius, the Allies should credibly underpin Ukraine’s accession prospects with a roadmap to the next NATO summits, scheduled to take place in Washington (2024) and in the Netherlands (2025). According to the Vilnius Communiqué, Allies will “review Ukraine’s progress on interoperability as well as additional democratic and security sector reforms”. The new NUC could monitor progress in these areas.
(2) The second work strand focuses on the weakening of Russia’s offensive military capabilities as long as Moscow is pursuing its aggressive, neo-imperial policy. The goal is to weaken Russia’s ability to compensate for military losses or modernize its armed forces. This can be achieved by imposing new sanctions aimed at the Russian defence industry and budget and by combatting sanctions evasion. In addition, third-party technology transfers to Russia must be stopped.
(3) The third work strand is about strengthening the resilience, defence and deterrence of the EU and NATO and securing long-term support for Ukraine. The Alliance must be prepared for the destabilization that could accompany a weakening of the Russian regime – for example, through power struggles like the one that involved the Wagner forces in June 2023. Moscow is likely to exploit any progress on NATO accession for propaganda purposes by depicting it as a threat to Russia with escalatory potential, not least as this view would resonate with pro-Russian discourses within certain NATO and EU states. Moreover, Russia could unleash its disruptive potential in the Balkans and Africa. Thus, strengthening Ukraine in the long term must go hand in hand with strengthening Western resilience. This includes proactively communicating the meaning, purpose and goals of Ukraine’s NATO membership to the populations of the Alliance, while at the same time clamping down on disinformation and taking action against institutions that claim to be part of civil society but are de facto controlled by the Russian state.
From Vilnius to Washington
In Vilnius, the G7, NATO and individual states launched a comprehensive support package to ensure Ukraine’s security in the long term. It is now crucial that these pledges are implemented and clearly framed as a bridge to Ukraine’s NATO membership; they must not be watered down as a substitute. Allowing any doubts about this end goal could have serious consequences because it would send a signal of weakness and doubting to both Ukraine and Russia.
Also crucial is the durability of Western support, which could dwindle over time owing to lack of interest, competing political priorities, domestic debates and changes of government. Indeed, Russia is betting precisely on Ukraine fatigue spreading among Western countries and paving the way for an eventual Moscow victory. Hence, credible implementation of support programmes is key. The 2024 NATO Washington Summit should take stock of progress made and draw conclusions about extending an invitation to Ukraine. And since progress towards accession presupposes Ukraine’s military success, systematic and long-term military support for Ukraine is a prerequisite for every debate within the Alliance. The more successful Kyiv is in defending against Russia, the more realistic its NATO accession becomes. And that outcome would contribute structurally to the stability and security of Europe itself.
Dr Margarete Klein is Head of the Eastern Europe and Eurasia Division.
Dr Claudia Major is Head of the International Security Division.
© Stiftung Wissenschaft und Politik, 2023
Stiftung Wissenschaft und Politik
ISSN (Print) 1861-1761
ISSN (Online) 2747-5107
(Updated English version of SWP‑Aktuell 44/2023)