Roundtable Blog: Toward Enforceable Security Guarantees
Editor’s Note:
This post is part of the PILPG Lawyering Justice blog’s roundtable series. Rather than a traditional co-authored piece, it presents a curated set of expert reflections from members of PILPG’s Ukraine Peace Negotiations Working Group. Drawing on the diverse expertise of our Peace Fellows, this roundtable-style blog explores the discussion surrounding security guarantees for Ukraine. Published under the Lawyering Justice banner, this post reflects our commitment not only to chronicling the legal and diplomatic dimensions of active conflicts, but also to fostering strategic foresight and connecting lawyering to policy planning. We hope this format will serve as a model for future collaborative work on peace and justice.
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In recent months, the question of credible and enforceable security guarantees for Ukraine has become central to its long-term defense and peace architecture. International partners have signaled new commitments—most notably through the Paris declaration of twenty-six states willing to support Ukraine’s security—but the substance and structure of these guarantees remain contested. The strategic landscape is shifting rapidly, and with NATO membership off the table for now, Ukraine and its allies must explore alternative legal and political frameworks capable of deterring further aggression and sustaining peace.
For this Roundtable Blog, we asked the Public International Law & Policy Group’s Ukraine Peace Negotiations Working Group to answer a set of four questions focused on different aspects of the security guarantee debate. Contributors were asked to assess elements of substantive and symbolic security guarantees; alternatives to NATO membership for Ukraine; legal and political frameworks for deploying multinational forces to Ukraine; and the feasibility of providing Ukraine with security guarantees absent Russia’s consent.
The purpose of this public-facing Roundtable Blog is threefold: to inform Ukrainian policymakers and Peace Formula stakeholders of the legal and strategic variables shaping the security guarantee debate; to connect Ukraine-focused expertise with broader international practice; and to provide analytically grounded perspectives that can guide the development of credible, enforceable guarantees in the months ahead.
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1. Substantive vs. Symbolic Commitments
What concrete elements would distinguish a truly substantive security guarantee for Ukraine from symbolic or rhetorical commitments, and are any states currently moving toward such substance?
Maj. Gen. Darrell Guthrie, Major General (Ret.) U.S. Army Reserve
Security guarantees must be understood as existing along a continuum of credibility. At one end lies the deployment of a robust military presence inside Ukraine—an option that few international partners are currently willing to pursue, but which would send the clearest signal of deterrence. As the continuum shifts outward, forward deployments in neighboring states such as Poland become more politically feasible, though still operationally demanding. Intelligence sharing, while ongoing and valuable, lacks the deterrent force of visible, deployable strength. Aircraft stationed in Germany or the UK may signal intent, but their strategic value increases significantly when positioned closer to Ukraine’s borders—or ideally, within Ukraine itself. Each step away from direct presence becomes increasingly symbolic. In case of using allied planes in Ukraine, partners would need to secure pre-negotiated overflight rights and territorial access agreements. Without these, even well-intentioned guarantees risk being undermined by logistical delays and political hesitation at critical moments.
Ambassador Joachim Rücker, former Special Representative of the UN Secretary-General and Head of the UN Mission in Kosovo
Expectations surrounding troop deployments must remain grounded in political and operational realities. Even under favorable conditions, no more than 40,000 troops from France, the UK, and other partners appear likely to be committed—and only after a ceasefire is in place. German ground deployments remain improbable given current domestic constraints, while all established forms of support from Germany will definitely continue or increase. In any case: what is needed, particularly in the post-ceasefire phase, is an “over-the-horizon” component—an arrangement that allows for quick activation of deterrent forces without immediate escalation. Such a model could offer credible deterrence while remaining politically palatable (the challenge lies in designing mechanisms that can evolve toward substance without overstretching the allies’ capabilities and without triggering premature confrontation). Even with these elements, the guarantees will likely fall somewhere between symbolic and substantive. In this vein, it will also be important to determine first and subsequent responders.
Professor Michael Kelly, The Senator Allen A. Sekt Endowed Chair in Law at Creighton University School of Law
Symbolic deployments can acquire strategic substance through deterrent effect and political signaling. Troops stationed in Ukrainian urban centers under national flags—not NATO—may initially appear symbolic. However, if Russian forces refrain from targeting these areas, the presence gains weight and transforms into a credible deterrent. The perception of risk alters behavior. Recent triggers of NATO’s Article 4, prompted by Russian drone incursions into allied airspace, suggest that the strategic calculus is shifting. These incursions have heightened awareness and urgency across Europe. The timeline matters: by February 2026, Russia will have been fighting Ukrainian democracy longer than Nazi Germany. That historical inflection point should catalyze European leadership and accelerate the transition from rhetorical support to enforceable commitments.
Ambassador Zorica Marić-Djordjević, former Head of the Permanent Mission of Montenegro to the World Trade Organization and Special Representative of Montenegro to the UN Human Rights Council
To transform political declarations into substantive guarantees, four foundational elements are required: legislation, funding, deployments, and treaties. At present, legislative progress among the 26 committed countries remains stalled. Written guarantees with specific operational plans are essential to move beyond symbolism. Europe’s €50 billion Ukraine Facility marks a starting point, but sustained funding and U.S. support remain critical. Deployment discussions are ongoing, yet lack clarity and coordination. Treaty frameworks—whether bilateral or multilateral—must be formalized to provide legal and political weight. Without these pillars, commitments risk remaining rhetorical. The urgency expressed by Ukrainian leadership, including President Zelenskyy’s request for a ten-day window to formalize guarantees, underscores the need to accelerate negotiations and codify intent.
Dr. Paul R. Williams, Rebecca Grazier Professor of Law and International Relations at American University
The central question is whether states are genuinely transitioning from symbolic gestures to enforceable commitments. Frameworks and funding mechanisms have been proposed, and political declarations have been made. Yet the movement toward operational substance remains uneven. The concept of “first responders”—states willing to act immediately in defense of Ukraine—has not been adequately explored. Without clarity on who will act, when, and under what legal authority, the credibility of guarantees remains in question.
Kateryna Kyrychenko, Head of Ukraine Legal Affairs and Program Management Kyiv, Ukraine
Several foundational elements must be resolved before security guarantees can be deemed robust. A temporal gap persists between Ukraine’s expectations and those of its international partners. Ukraine seeks engagement and protection now—not only after a ceasefire. Many so-called guarantees, such as intelligence sharing, do not involve physical deployment. Presence on the ground adds credibility and shifts the perception of commitment. Recent Russian drone incursions have intensified the European security discourse. The strategic environment is evolving rapidly, and guarantees must evolve with it.
2. Deterrence Without Article 5
If NATO membership remains off the table, what combination of bilateral, coalition, or EU-led guarantees could approximate the deterrent effect of Article 5—or is that fundamentally unattainable?
Ambassador Ylber Hysa, former Ambassador of the Republic of Kosovo to Montenegro and North Macedonia
The concept of security guarantees must be disaggregated. NATO membership for Ukraine remains politically blocked, but the broader question is whether NATO itself can still credibly protect its members. Recent Russian provocations—including drone incursions and hybrid operations—challenge the assumption that Article 5 will be automatically triggered. The line between Article 4 (consultations) and Article 5 (collective defense) is increasingly thin, and Russian actions appear designed to test that boundary. These provocations raise doubts about NATO’s internal cohesion and response mechanisms. Security guarantees for Ukraine are not just about Ukraine—they are a strategic investment in NATO’s credibility. If provocations continue, the question becomes: where is the red line, and what would shift the alliance from Article 4 consultations to Article 5 activation?
Sindija Bēta, Legal Officer, PILPG
Past agreements, which focused on consultations, failed Ukraine. The Budapest Memorandum of 1994, which did not deter the events of 2014 nor 2022, demonstrates that non-binding assurances do not prevent aggression. A more viable path could lie in EU membership. The EU Treaty contains a defense and security provision under Article 42(7). Russia has not objected to EU membership for Ukraine. Ukraine should aim to anchor its long-term security within the EU framework, where legal obligations and political and economic integration offer a potentially stable foundation.
Ambassador Joachim Rücker, former Special Representative of the UN Secretary-General and Head of the UN Mission in Kosovo
The EU Treaty offers (in its Article 42,7) a robust foundation for long- and maybe mid-term security guarantees. Nevertheless, in the short term, guarantees must be defined within a clear framework that outlines lines of response and escalation management. Even a symbolic military presence, if politically well coordinated and legally framed, can become substantive. The deterrent effect lies not only in capacity but in clarity of commitment. The EU’s mutual defense clause, while less operationalized than NATO’s Article 5, can serve as a credible basis for coalition-led guarantees in the long-term.
Ambassador Zorica Marić-Djordjević, former Head of the Permanent Mission of Montenegro to the World Trade Organization and Special Representative of Montenegro to the UN Human Rights Council
The most realistic immediate layer of guarantees for Ukraine involves air and missile defenses. These systems are essential to protect civilians, ports, energy infrastructure, and industrial assets from Russian strikes. Expansion of Patriot or similar systems, acceleration of European sky defense initiatives, and integration of early radar warning systems with NATO are critical steps. These measures do not replicate Article 5, but they approximate its deterrent effect by reducing vulnerability and signaling readiness. Ukraine must also strengthen its own military capacity in parallel to ensure sustainability and resilience. The credibility of external guarantees depends not only on what partners provide, but on Ukraine’s ability to absorb, deploy, and maintain those systems over time.
H. E. Dr. Igor Luksic, the former Prime Minister of Montenegro
Security guarantees very much depend on the context and need to be seen as part of a comprehensive approach to ending of the current war. In order to define appropriate security guarantees (related to the present and the future), it is important to understand what is the treatment of the currently invaded territories. Whenever the peace agreement is reached, the Ukrainian security in general will be inextricable from the law enforcement in that region, as well as its economic stabilization and development. To that end, it is important to closely monitor what happens and if anything happens at all with regard to the Gaza Strip and the so-called GITA idea, as it appears to have the possibility to become a kind of model to, with necessary adaptation, use it in similar cases. Additionally, it is hard to imagine any model reached without the eventual mandate of the UN Security Council. In my view, it may be of interest to also take a look at the status of the Trusteeship Council, as it still formally exists and is stipulated by the UN Charter. Contrary to its original role, in this case, it may provide a legal framework for the period between the peace agreement and, hopefully, eventual EU membership of Ukraine.
3. Legal and Political Frameworks for Deployment
What legal or political frameworks could authorize the forward deployment of multinational forces into Ukraine—whether as trainers, peacekeepers, or deterrent forces—before a ceasefire is reached?
Maj. Gen. Darrell Guthrie, Major General (Ret.) U.S. Army Reserve
Authorization frameworks must be grounded in sustainability. Forward deployment before a ceasefire remains politically sensitive, but the question of long-term viability is paramount. Ukraine receives a wide array of weapons systems, yet the sustainability model remains unclear. Battlefield damage, logistical strain, and replenishment cycles require structured planning. Air and missile defense systems are critical, but must be embedded within a broader framework that supports Ukraine’s ability to defend itself over time. Ukraine possesses a manufacturing base capable of supporting such efforts, but coordination is essential. The U.S. continues to work on artillery ammunition commitments, signaling intent but also revealing delays. Structured deployments—whether trainers, peacekeepers, or deterrent forces—must be framed as part of a multi-year commitment, not subject to shifting political winds. Legal frameworks must reflect that continuity.
Kateryna Kyrychenko, Head of Ukraine Legal Affairs and Program Management Kyiv, Ukraine
Hesitation among international partners to authorize forward deployment before a ceasefire is understandable, but alternative forms of guarantees already exist. Sanction-based guarantees, for example, offer conditional leverage. Presence on the ground, even in non-combat roles, introduces risks of escalation and political backlash. The deterrent effect of such deployments depends not only on legal authorization but on strategic signaling. For many partners, the possibility of direct confrontation with Russia remains the primary deterrent. Engagement levels vary across states and will likely evolve in phases. Legal frameworks must accommodate differentiated participation and phased escalation, allowing some states to engage earlier through training missions or monitoring roles, while others commit to deterrent deployments post-ceasefire.
Ambassador Zorica Marić-Djordjević, former Head of the Permanent Mission of Montenegro to the World Trade Organization and Special Representative of Montenegro to the UN Human Rights Council
The next step in operationalizing guarantees lies in predictable, multi-year military funding. The EU and U.S. must pass and adopt aid packages that guarantee supply chains and defense capabilities over time. Without sustained funding, deployments risk becoming episodic and politically vulnerable. To deter Russia from exploiting a ceasefire, rapid response commitments must be formalized—drawing lessons from Bosnia’s Berlin Plus post-conflict arrangements. Legal frameworks should enable pre-authorized activation of multinational forces in response to violations or provocations, rather than relying on ad hoc political consensus. Forward deployment, even in limited roles, must be embedded within a broader architecture of readiness, deterrence, and legal clarity.
Professor Michael Kelly, The Senator Allen A. Sekt Endowed Chair in Law at Creighton University School of Law
Historical precedent offers guidance. In the 1990s and early 2000s, the UN framework was used to authorize multinational action—sometimes directly, sometimes through creative interpretation. The first Iraq war relied on explicit Security Council resolutions; the second manipulated existing mandates. Today, the challenge lies in Russia’s veto power. Any Security Council initiative must navigate that obstacle. Yet precedent shows that legal creativity, coupled with political will, can produce frameworks that authorize action even in contested environments.
4. The Role of Russia
Is it possible to design security guarantees for Ukraine that are effective and enforceable without Russian consent, or does any durable arrangement inevitably require Moscow’s participation or at least acquiescence?
Ambassador Joachim Rücker, former Special Representative of the UN Secretary-General and Head of the UN Mission in Kosovo
This question increasingly guides strategic discussions in capitals such as Rome and Berlin. A growing chorus of foreign observers argues that without Russian consent, any forward-looking security guarantees lack realism. This view, however, risks eventually delaying the deployment of ground forces and discouraging the 26 states currently engaged (which include Italy and Germany). The absence of Russian acquiescence becomes a political constraint, not just a legal one. But the UN Security Council remains a potential avenue. Despite the risk of a Russian veto, the Council offers a framework that brings Moscow to the table—even if only procedurally. Recent remarks by President Trump, which reaffirm the UN’s relevance while criticizing its effectiveness, create a tactical opening. That momentum should be harnessed. Rather than abandoning the UN, efforts should double or triple there in order to draft, discuss and secure a resolution that legitimizes a coalition-led guarantee. The presence of Russia, even as an obstructive actor, may paradoxically strengthen the legal and diplomatic foundation of the initiative.
Dr. Paul R. Williams, Rebecca Grazier Professor of Law and International Relations at American University
Diverging opinions persist within the EU on whether Russian consent is a prerequisite. Some argue that engaging Moscow too early risks derailing the coalition’s internal consensus. Others believe that any durable arrangement must eventually confront the question of Russian acquiescence. The sequencing of engagement matters. Can the 26 build a coherent proposal before involving Russia? And what legal instruments would underpin such a coalition? A signed memorandum? A UN resolution? A treaty-based framework? These questions remain unresolved, but they are central to the credibility of any future guarantee.
Ambassador Elayne Whyte Gomez, Senior Fellow of the UN Institute for Disarmament Research, Professor at Johns Hopkins School of Advanced International Studies, and former Ambassador and Permanent Representative of Costa Rica to the United Nations
The role of Russia must be addressed, but not prematurely. Discussing Russian involvement too early risks freezing progress among Ukraine’s partners. A phased approach may be more effective: first, build a solid proposal among the 26; then, engage Moscow with a unified front. The legal basis for a coalition of the willing must be clarified. Article 51 of the UN Charter—Ukraine’s right to self-defense—offers a foundational framework. Beyond that, the UN General Assembly, while not legally binding, provides a strategic theater to challenge prevailing narratives and build diplomatic momentum. The distinction between UNGA and UNSC pathways must be understood not only in legal terms but in political signaling.
Ambassador Ylber Hysa, former Ambassador of the Republic of Kosovo to Montenegro and North Macedonia
The essential debate is not whether the UN is good or bad—it is whether the UN is viable under current conditions. As it stands, Russian consent appears unlikely. The UN Security Council is not a realistic avenue in the near term. Alternatives must be explored. What can be done without Russian participation? What legal instruments exist outside the UN framework? Three tracks should be pursued in parallel: one through the UN, one without Russian consent, and one with Russian consent if conditions change. Each track must be developed with contingency planning and legal rigor.
Ambassador Zorica Marić-Djordjević, former Head of the Permanent Mission of Montenegro to the World Trade Organization and Special Representative of Montenegro to the UN Human Rights Council
Russia’s position is clear and vocal. Foreign troops and NATO-style guarantees on Ukrainian territory are red lines. Any coalition of the willing must be framed carefully. Several legal bases exist. First, Article 51 of the UN Charter allows Ukraine to invite other states to assist in its defense—this is already the foundation for current Western training and aid missions. Second, treaty or political commitments can formalize bilateral or multilateral guarantees. Third, EU and NATO instruments—such as Berlin Plus—offer operational models, as seen in post-Bosnia deployments. These frameworks do not require Russian consent but must be designed to withstand political and legal scrutiny.