Providing long-term security for Ukraine: NATO membership and other security options

As Russia’s unjustified war against Ukraine continues, a critical question will be whether and how NATO should enhance its support for Ukraine at its July summit in Vilnius, Lithuania. NATO has long stated that Ukraine will—eventually—become a member of the alliance, but a key decision for NATO will be how to implement that promise in the context of the ongoing war.

This issue brief evaluates membership and other security options for the alliance and its members to consider. The options range from formal actions by NATO as a whole to collective or individualized efforts by member nations. The brief recommends that for geopolitical and values-based reasons, the alliance should, at a minimum, offer Ukraine a Membership Action Plan (MAP) or its equivalent supported by security guarantees that will help ensure success in its fight against Russia and strengthen security in Europe for the long term.

I. Background: The failure of deterrence

The February 2022 invasion of Ukraine by Russia rests in significant part upon the historical context of a Russian desire for empire that has long challenged Ukraine’s separate identity. That separate identity was, however, recognized by Russia in the 1991 Belovezha Accords and then formally validated by the 1994 Budapest Memorandum to which Russia, the United Kingdom, and the United States are signatories along with Ukraine. France and China provided additional assurances in separate documents. The memorandum explicitly provides for Russia as a signato-ry to “respect the independence and sovereignty and the existing borders of Ukraine,” and to “refrain from the threat of the use of force or the use of force against the territorial integrity or political independence of Ukraine.”1

Russia, of course, has ignored its pledged word, first undertaking the 2014 invasion of Crimea and the subsequent military activities in the Donbas region of Ukraine and then the full-scale invasion beginning February 2022. Underlying such actions is the worldview held by Russian President Vladimir Putin. “We are one people” is how he chooses to describe Russia and Ukraine, with Ukrainian sovereignty possible only in conjunction with Russia. That viewpoint has been a fundamental driver of Russian behavior toward Ukraine since President Putin came to power, though he only formally challenged Ukrainian sovereignty starting in 2014. Putin also has articulated a long list of grievances including purported security concerns against the United States and NATO, notably beginning with his speech at the 2007 Munich security conference.

For their part and by contrast, the people of Ukraine have increasingly aligned themselves with the transatlantic nations including through the Orange Revolution in 2004 and the Maidan Revolution of Dignity in 2014. Part of that alignment includes a desire to join the European Union (EU), for which the formal process of membership has now begun, and part has included a desire to join NATO built on multiple years of interactions.

Ukraine’s partnership involvement with NATO is long-standing. Ukraine joined the North Atlantic Cooperation Council in 1991, the Partnership for Peace in 1994, and the Charter on Distinctive Partnership (and the NATO-Ukraine Commission) in 1997. A NATO Information and Documentation Center and a Liaison Office were established in 1997-1999. NATO partnership arrangements allowed Ukraine to participate in multiple NATO operations and exercises and to receive military assistance.2

In 2002, President Leonid Kuchma expressed interest in Ukraine joining the alliance and in 2008 President Viktor Yushchenko sought a Membership Action Plan for the country. Moscow firmly opposed the proposal.

In April 2008, a divided NATO summit in Bucharest declared that Ukraine and Georgia “will become members” of NATO but without a time frame—agreeing only to begin a period of intensive engagement to address outstanding questions including each country’s application for a MAP. Membership, of course, was not achieved; neither was entry into the MAP process. Moreover, that statement of policy arguably was a factor—among many others—leading to Russian invasions of both Georgia and later Ukraine.

In 2010, under pro-Russian President Viktor Yanukovych, Ukraine withdrew its candidacy for NATO membership and adopted a nonaligned status. After the 2014 Maidan protests, whose original cause was Yanukovych’s refusal to sign as he had promised an association agreement with the European Union, and Russia’s initial military action against Ukraine, NATO designed in 2016 a comprehensive assistance package for Ukraine. In 2017, the Ukraine parliament reversed itself and reinstated NATO membership as a strategic goal. Two years later, a constitutional amendment supporting NATO membership went into effect. Ukraine was invited to become an Enhanced Opportunity Partner in 2020 and after the 2022 invasion, Kyiv formally applied for NATO membership.3

The conclusion to be drawn from this history is that ensuring Ukraine’s long-term security will require mechanisms that extend well beyond those that have failed Ukraine in the past. The failures of deterrence in 2014 and 2022 occurred despite Russia’s Budapest Memorandum assurances, the series of partnership arrangements between NATO and Ukraine described above, the threat of massive Western sanctions prior to the February 2022 invasion, and the various Western efforts to provide Ukraine with military assistance prior to the war (including $2.7 billion from the United States between 2014 and 2022).

Failure of deterrence in the past and the risk that it could fail again in the future is the principal reason that NATO should take additional steps at the Vilnius summit to bring Ukraine closer to alliance membership.

A start has been made in this regard. During the first year of the war, the United States provided about $47 billion in military aid and $30 billion in economic assistance to Ukraine.4 European institutions and countries during this period committed a total of €54.9 billion to Ukraine, with Germany providing the largest amount.5

Moreover, NATO, through statements by Secretary General Jens Stoltenberg, and multiple heads of nations have declared that supporting Ukraine’s independence is critical for both security and value-based reasons. As French President Emmanuel Macron has said, Russia’s full-scale invasion “flouts the principles of the only international order possible, the only order that can guarantee peace; in other words, respect for national sovereignty and intangible borders.”6 Similarly, as Finland’s prime minister, Sanna Marin, has stated, Ukrainians “are representing all of our values, European values, and they are fighting for us, all of us.”7 Likewise, European Commission President Ursula von der Leyen has been clear: “You can count on us. We will continue to provide our full support. Now… and for the future.”8

The issue now facing NATO and Ukraine is how statements like these can be translated into specific security initiatives.

II. Why NATO membership for Ukraine?

There is a strong case for Ukraine to become a NATO member, but there are also some hurdles to overcome.

A. The case for Ukraine joining the alliance

There is a strong case for Ukrainian membership in NATO. The most obvious argument is that deterrence based on assurances, partnerships, threat of sanctions, and military assistance has failed Ukraine twice. For the long-term security of Europe, deterrence cannot be allowed to fail again. This is especially true with regard to a country that has sacrificed so much for its freedom. It has fulfilled most of the criteria of the Membership Action Plan, including the economic, political, and military requirements. Ukraine deserves NATO’s full protection. With the guarantee of long-term security, Ukraine will be able to participate in any future negotiation with Russia with greater confidence. In addition, during the past fifteen months of conflict, Ukraine has built firm cultural, political, and security bridges with all NATO members and with the European Union. Importantly, NATO membership for Ukraine would not be a one-way street. Ukraine’s military is one of the most capable and certainly the most battle tested in Europe. They are fully trained on a wide array of NATO munitions and thus interoperable with NATO forces. Their knowledge of how Russia fights would be of incalculable value to the alliance.

B. Hurdles to membership

Membership of course requires all existing NATO members to concur and ratify the agreement. The fact that Swedish membership has been held up by two countries based on extraneous reasons is a reminder that membership for Ukraine may not be easy to attain. Actual membership before the current conflict ends is unlikely because several countries fear that NATO would immediately be drawn directly into that fight. Other NATO nations even appear reluctant to concur if Russian troops continue to occupy some Ukrainian territory, fearing that this could eventually trigger Article 5 of the Washington Treaty. Some have pointed to the high level of pre-war corruption in Ukraine and insist that progress is needed to reverse this situation. Any plan to bring Ukraine quickly into the alliance will need to contend with these hurdles.

III. NATO membership options

As it prepares for the Vilnius summit, NATO is considering ways it might approach the question of NATO membership for Ukraine.

A. The nature of a NATO commitment

A good place to start an analysis of NATO membership options for Ukraine is with the NATO treaty itself to understand the effect and obligations that Ukraine’s membership in NATO would establish.

Articles 3 and 4 of the treaty have important provisions providing, respectively, for “develop[ing] individual and collective capacity to resist armed attack,” and “consult[ing] together whenever, in the opinion of any of them, the territorial integrity, political independence or security of any of the Parties is threatened.”9 It should be apparent that, de facto, these provisions already describe Ukraine’s own actions and its interactions with NATO.

However, the heart of the NATO treaty is Article 5, whose key paragraph provides the following:

The Parties agree that an armed attack against one or more of them in Europe or North America shall be considered an attack against them all and consequently they agree that, if such an armed attack occurs, each of them, in exercise of the right of individual or collective self-defence recognised by Article 51 of the Charter of the United Nations, will assist the Party or Parties so attacked by taking forthwith, individually and in concert with the other Parties, such action as it deems necessary, including the use of armed force, to restore and maintain the security of the North Atlantic area.10

The important point to take from the wording is that while an attack against one automatically triggers the Article 5 commitment, the “forthwith” response by a nation is by “such action as it deems necessary” which could be “including the use of armed force.”

Analytically, therefore, and according to the words of the treaty, there is no requirement of unanimity before a member can take “such action as it deems necessary.” Action can even be done “individually.” To be sure, the whole point of the NATO integrated military structure is to generate collective responses but no one member can stop others from acting with national capabilities—which are the very great majority of the capabilities that are available to the alliance. Thus, while it almost certainly would make geopolitical sense to have the North Atlantic Council (NAC) authorize any NATO action, nations do not have to wait for the NAC to take steps that nonetheless fall within the treaty.

On the other side of the coin, a nation might choose not to be part of a collective effort. France’s disengagement from the integrated military structure for many years but continued membership in the alliance is illustrative. Hypothetically, though extremely unlikely, even if Ukraine became a member of NATO in the near term, the other members could choose to provide only the type of support that Ukraine is already receiving.

The ability to calibrate responses could become important under certain circumstances, as dis-cussed below. However, while individual NATO nations would have the choice of how to respond to “an attack on one,” media reports suggest that at least some nations are concerned that premature membership for Ukraine will drag them into an unwanted war.

B. Borders to be defended, and the challenge of continuous low-level conflict

The current phase of the Ukraine-Russia war will end. How and when is not yet clear. The outcome of this phase will depend in part on the West’s ability to provide Ukraine with adequate weapons and in part upon Ukraine’s own actions, including the success of the anticipated Ukrainian counteroffensive. Russian capabilities and geopolitical considerations, of course, also come into play. Possible outcomes include the following:

A Russian military defeat and successful Ukrainian effort to regain all or substantial parts of its occupied territory, leading to a negotiated end to the war on terms acceptable to Ukraine
A continued low-level conflict including changes in the effective line of control
A new cease-fire line formed wherever the fighting stops—with Russian troops still on some Ukrainian territory. A Russian conquest of the entirety of Ukraine is seemingly less likely.

If the past several years are any guide, they suggest the difficulty of accurately anticipating the future—and for that reason, NATO may wish to build a degree of flexibility into any agreements with Ukraine that are made at the Vilnius summit. Nonetheless, at such time as Ukraine becomes a member of NATO, a decision would have to be made as to precisely which borders NATO would be obliged to defend. That would not be difficult if Ukraine successfully regained its pre-2014 borders. But if the cease-fire line includes continued Russian occupation of Ukrainian territory, the situation would be more complicated. Ukraine would have to describe for NATO the territory and borders that would fall within the scope of the treaty, and NATO would have to agree.

Ukraine would understandably want to regain the entirety of its territory, and NATO presumably would not recognize any Russian claim to the contrary. The question thus arises as to what NATO’s position would be if Ukraine used force to retake occupied territory once it had become a NATO member. A somewhat related question would arise if despite an agreement for a cease-fire, there continued to be low-level conflict instituted from Russia-controlled territory, and Ukraine determined it needed to respond. At this time, a NATO consensus for membership would be unlikely if members thought Ukraine—post cease-fire and membership—would seek, without further Russian aggression, to retake additional occupied territory, thus initiating the prospect of a war between Russia and NATO. Inasmuch as the issue facing NATO is not immediate membership for Ukraine, however, that question and the issue of responding to low-level conflict could be left to the future to be analyzed in the context of an actual membership offer.

C. Membership options for the Vilnius summit

With the foregoing as background, the discussion below sets forth five possible approaches to Ukrainian membership in NATO that would create a stronger perspective for NATO membership and should be considered at the Vilnius summit.

1. Offer fast-track membership without conditions upon a cease-fire satisfactory to Ukraine

NATO could declare at the Vilnius summit that Ukraine has already met most of the criteria set forth for candidates in the Membership Action Plan. Those criteria are not a check list and have varied over time, but in general the principal criteria for membership have been the following:

New members must uphold democracy and the rule of law, including tolerating diversity.
New members must be making progress toward a market economy.
New members must be security providers with their military forces under firm civilian control and working toward compatibility with NATO forces.
New members need to settle their international disputes by peaceful means except if responding to unlawful use of force, armed attack, or other violation of international law.

A summit declaration could state that all such criteria have already been met, and that like Finland and Sweden, an MAP process is no longer needed for Ukraine. An offer of membership could then follow upon a cease-fire satisfactory to Ukraine.

Under this option, NATO would not seek any assurances from Ukraine regarding its future efforts to regain any occupied territory that Russia might hold after a cease-fire. Without these assurances, Ukraine would not be subject to any agreed constraints barring it from using force subsequently to retake lost territory. However, as a practical matter, Ukraine probably could not undertake such an action effectively without the support of NATO nations for sustainment, intelligence, logistics, and other military capabilities. Accordingly, NATO would have significant influence on Ukrainian decision-making.

Finally, it should be apparent that while such an approach has elements of being a “fast track,” it arguably incentivizes Russia not to enter into a cease-fire.

2. Offer fast-track membership upon a cease-fire satisfactory to Ukraine but with newly designed conditions

This option would be similar to the first in that it would bypass the existing MAP process for Ukraine. The argument would be that Ukraine deserves to be treated more like Finland and Sweden, where an MAP process was not required. But it would recognize that Ukraine has certain problems that Finland and Sweden did not have. Rather than setting no conditions for membership, NATO would create new criteria or metrics specifically designed for Ukraine.

Those new criteria would be developed based on what it would take to gain a NATO consensus for membership. In addition to an agreed cease-fire, those conditions might include the below:

Assurances from Ukraine that it would use means other than armed force to regain any remaining occupied territory. NATO would take on obligations to continue to put significant economic and diplomatic pressure on Russia to return any occupied territory. Such assurances would not preclude Ukraine from defending itself from Russian attacks.
Assurances consistent with those required in conjunction with Ukraine’s candidacy to the European Union including reduction of corruption, judicial independence, and protection of all minority rights.

This option could expedite Ukrainian membership in NATO. But the admissions process would not be free of conditions. It would be a significant step toward Ukrainian membership but would still give NATO nations control over the subsequent process.

3. Offer a traditional Membership Action Plan plus guarantees for continued military and economic support

This option would do what the United States originally proposed for the 2008 Bucharest summit. It would state that the “period of intensive engagement to address outstanding questions” agreed to in Bucharest had successfully taken place and that it is time to take the next step. It would be a more burdensome process for Ukraine and could allow the alliance to set the pace for future membership. Additional criteria could be added as needed to gain a political consensus. NATO has utilized the MAP process for multiple countries that have joined the alliance as well as for some that are still aspirants. NATO has summarized the MAP as follows:

The Membership Action Plan (MAP) is a NATO programme of advice, assistance and practical support tailored to the individual needs of countries wishing to join the Alliance. Participation in the MAP does not prejudge any decision by the Alliance on future membership….Upon decision of the North Atlantic Council, countries participate in the MAP by submitting individual annual national programmes on their preparations for possible future membership. These cover political, economic, defence, resource, security and legal aspects. The MAP process provides a focused and candid feedback mechanism on aspirant countries’ progress on their programmes. This includes both political and technical advice, as well as annual meetings between all NATO members and individual aspirants at the level of the North Atlantic Council to assess progress, on the basis of an annual progress report. A key element is the defence planning approach for aspirants, which includes elaboration and review of agreed planning targets. Throughout the year, meetings and workshops with NATO civilian and military experts in various fields allow for discussion of the entire spectrum of issues relevant to membership. 11

For Ukraine, the MAP process presumably would be enhanced by continued military and economic support—the nature of that support being significantly affected by whether the military conflict with Russia was still ongoing. However, a pledge of a MAP plus ongoing support would be very reassuring.

4. Create a new type of NATO-Ukraine partnership designed to ensure long-term security assistance and eventual membership

This option would also set aside the requirement for a MAP, and create a new partnership arrangement for Ukraine designed to both provide ongoing security assistance and lead eventually to membership. For example, Ian Brzezinski and Alexander Vershbow have proposed establishing “a new NATO-Ukraine Deterrence and Defense Partnership (DDP).”12 Building on Ukraine’s status as a member of the Enhanced Opportunities Partnership program, the DDP would build up Ukraine’s long-term capacity to defend itself and deter any future Russian aggression. Allies’ commitment to arm, train, and equip Ukrainian forces—backed, if possible, by NATO common funding—would serve as a post-war security guarantee for Ukraine until allies are ready to admit Ukraine as a full-fledged NATO member.

This partnership approach would be offered as an alternative to a NATO MAP, but like a MAP its objective would be to facilitate Ukraine’s preparation for eventual membership in the alliance. Such a program would open the door to direct accession by Ukraine as was offered to Finland and Sweden.

In substance, the suggested DDP is a promise to continue doing what the alliance members are already undertaking with respect to Ukraine’s capacity to defend itself against Russia, plus to-be-determined activities to “facilitate Ukraine’s preparation for eventual membership.”

5. Repeat NATO’s Bucharest summit language, but in addition task a high-level group to set a path for Ukrainian membership by a target date

If the heads of state are deadlocked on this issue at Vilnius, the summit documents could simply restate the Bucharest summit language and NATO’s “open door” policy. In light of Russian aggression in Ukraine, however, a simple repetition of a failed NATO policy would seem unwise. Yet if a consensus cannot be built for one of the other options, this might be NATO’s default position. Should NATO’s leadership be faced with this situation, one way to demonstrate progress toward Ukraine membership would be to establish a high-level group to create an implementation path and to set an early target date for Ukrainian membership.

IV. Possible non-NATO options

Establishing NATO membership for Ukraine would be the surest way to provide long-term security for the country. But there are other multilateral and unilateral suggestions that could complement NATO membership and, though weaker, could, if necessary, substitute for it should consensus fail at Vilnius. These efforts could be launched whatever the decision about Ukraine’s relations with NATO.

A. Other possible multilateral initiatives

1. Convert the current Ukraine Defense Contact Group of fifty-four nations into a permanent arrangement. The group could declare that after a cease-fire they will continue to supply Ukraine with all the weapons it needs to deter renewed Russian assaults. Such a declaration would make clear to Russia that Ukraine can count on continued Western military support and thus would enhance deterrence.
2. Create a smaller core group of major countries similar to AUKUS (the Australia, United Kingdom, and United States trilateral security pact) designed to provide high impact weapons to Ukraine. Such a group would commit to sharing top-of-the-line technology with Ukraine over time. It would include major NATO members such as France, Germany, Poland, the United Kingdom, and the United States. It could serve as a steering group for the larger group of fifty-four arms donors.
3. Have nations adopt language similar to that in the Taiwan Relations Act (TRA). The TRA states that the United States would have “grave concern” should China attack Taiwan and commits the United States to providing Taiwan with military equipment to defend itself.13 The defense commitment in the TRA is not absolute and efforts are being made in the United States to strengthen it. Yet it has been sufficient to deter China for over four decades. Having multiple nations undertaking such a common commitment could be of substantial value. The United States would likely have to take the first step. However, legislative action in the United States and elsewhere may be difficult to obtain.
4. Accelerate Ukrainian membership in the European Union, which would extend the Article 42.7 EU defense commitment to Ukraine. The European Union has granted candidate status to Ukraine. It remains unclear how long it would take for Ukraine to become a full EU member under normal circumstances. But Brussels could accelerate the process given the unusual circumstances. While generally considered weaker than NATO’s Article 5 defense commitment, Article 42.7 does create an “obligation of aid and assistance … by all means in their power” in case of armed aggression against the EU member.14 This commitment was considered inadequate to deter by Finland and Sweden when they decided to join NATO. Nonetheless, it could cause Russia to rethink further military aggression against Ukraine.
   B. Possible unilateral US initiatives
5. Pass a concurrent resolution pledging to continue to provide necessary weapons to Ukraine after a cease-fire to ensure that Russia does not have the advantage to attack Ukraine again. This kind of congressional commitment, though not binding, would at least put Russia on notice that despite some opposition, Congress would pursue support for Ukraine “as long as it takes.” That might discourage Russia from pursuing a long-term war.
6. Declare Ukraine to have major non-NATO ally (MNNA) status. Currently nineteen nations have MNNA status—none of them in Europe. This US designation confers military and financial advantages to the recipient. But it does not convey a firm defense commitment. It could nonetheless be symbolically important, though it does risk conveying the impression that NATO membership is off the table.

While a US-only commitment would be credible, it likely would be politically less attractive to Congress than a multilateral approach.

C. The “Israel Model” option

Some have suggested the “Israel Model” as an approach for long-term Ukrainian security. This would include agreement to provide a certain level of annual military support and a moral commitment to come to the nation’s rescue if needed. This might be provided on a multilateral or bilateral basis. But Israel’s security situation is quite different from Ukraine’s. Israel’s conventional military is capable of defeating any combination of hostile neighbors. It has treaties and informal agreements with most of its neighbors which further assure its security. It produces its own high technology armaments. And it has a nuclear deterrent force which provides for its ultimate security. Ukraine has none of these assets. Its conventional defense requirements far outpace those of Israel. While pledges of sufficient levels of annual military support would be useful to Ukraine, the “Israel Model” alone would be inadequate to provide for Ukraine’s long-term security.

V. Assessing the options

To assess the array of multilateral and unilateral options presented above, there are six considerations that should shape the approach to providing Ukraine with support for its security at the Vilnius summit.

Commitments should be as multilateral as possible. It is important to make clear to Russia that the full NATO alliance stands behind Ukraine.
Commitments should be as realistic as possible, and designed to practically advance Ukraine’s interests and its movement to NATO membership.
Commitments should be as clear as possible with regard to the intention to support Ukraine over the long term so that Russia does not think it can outlast NATO support to Ukraine.
Commitments should be designed to both deter further Russian aggression and prevent a wider war in Europe.
Commitments should not constrain Ukraine’s ability to determine for itself whether and how to negotiate with Russia.
Commitments should be supported with the necessary financial resources.

VI. Conclusions and recommendations

In assessing the various options to provide Ukraine with longer-term stability and in light of the six considerations above, we offer the following conclusions and recommendations for both NATO and Ukraine to consider:

NATO membership would provide the strongest long-term deterrence against renewed Russian aggression, but the difficulty Sweden is having in securing Turkish and Hungarian approval of NATO accession indicates the difficulty that Ukraine might have. Seeking immediate NATO membership amid armed conflict would probably not succeed since it would create an immediate Article 5 situation.
Careful coordination will be needed before the Vilnius summit to ensure that the membership issue does not divide the alliance as it did at the Bucharest summit. Nonetheless, NATO should take additional steps at Vilnius to create a clear perspective for Ukrainian membership. Accelerated planning for this outcome must start now.
There are several options as described above that NATO should consider for the Vilnius summit. At a minimum, NATO should offer Ukraine a Membership Action Plan plus assurances of continued military and economic support. Initiating the MAP now would still allow NATO to control the pace of the process. NATO might also set a target date for membership.
Alternatively, the summit could set aside the MAP process and create new membership criteria or metrics specifically designed for fast-track membership, as outlined in Option 2.
Other multilateral and bilateral commitments as described above could also be made. In general, multilateral or coordinated unilateral commitments would be more feasible and valuable.
NATO should be clear on how Ukraine would eventually fit into overall NATO military planning. The operational requirements for Ukraine’s NATO membership would need to be assessed. Appropriate coordination would be necessary should Ukraine join NATO after an agreed cease-fire has been reached or under other circumstances.
NATO should also be clear on what borders will be defended and how any occupied territories or violations of a cease-fire would be dealt with including responding to low-level conflict. The alliance should evaluate in advance what might be appropriate responses if Ukraine were to become determined to regain territory that remained under Russian control after a cease-fire. Decisions on these issues would need to be made before a final invitation for membership is issued.
In any case, whatever options NATO chooses, it should affirm in ways that convey seriousness of purpose its 2008 commitment that NATO membership is the ultimate destination for Ukraine.