Peace negotiations often make headlines with political agreements and carefully staged handshakes. Yet it is the detailed legal work behind the scenes leading up to these historic moments that determine whether they result in lasting outcomes.

In 2025, a White & Case team partnered with the Public International Law & Policy Group (PILPG), a global pro bono law firm and longstanding pro bono client, to address one of the most complex challenges in Ukraine’s pursuit of peace: how the international community can provide credible security guarantees to Ukraine, including if membership in the North Atlantic Treaty Organization (NATO) is not an option.

Designing credible security guarantees

Security guarantees are expected to form one of the three central components of any sustainable settlement for Ukraine, alongside territory arrangements and the disposition of frozen sovereign assets. In this context, security guarantees refer to formal legal commitments through which other states or international organizations pledge to protect Ukraine against future aggression.

Ukraine’s history underscores the stakes. In 1994, Kyiv relinquished its nuclear arsenal in exchange for commitments that later proved unenforceable and insufficient. Thus, the challenge today is to craft agreements that are strong enough to deter future aggression, precise enough to be implemented by government and militaries, and legally grounded so that obligations are clear and enforceable under international law.

"Mapping out security guarantees is particularly challenging," explains PILPG’s co-founder Dr. Paul Williams. "They cannot simply be copied from existing alliances or past agreements. Each arrangement must reflect the specific political needs, legal foundations and realities of the parties involved."

Guarantees can take various forms, including mutual defense commitments, deterrence-by-armament strategies, pledges of military assistance or peacekeeping frameworks. Each model raises complex legal questions, such as the mechanisms for triggering obligations, the definition of rules of engagement, the criteria for determining whether a breach has occurred, the structure of command arrangements and the allocation of responsibility if a ceasefire collapses.

Putting security guarantees to the test

White & Case played a critical role in stress-testing potential security guarantees. The team conducted a rigorous legal analysis of hypothetical enforcement scenarios, examining how proposed guarantees would operate in real time during a crisis.

Our lawyers assessed how obligations might be interpreted during renewed hostilities, how disputes over compliance could unfold and how ambiguities in drafting might affect decision-making. This analysis mirrors the precision used in high-stakes commercial agreements—anticipating counter-positions, identifying implementation gaps and ensuring clarity in operative language.

"Security guarantees are a conundrum," says Williams. "They require precise and practical drafting to ensure they can be implemented—the kind of work lawyers perform daily for commercial clients, but rarely in a geopolitical context."

Clarity in drafting is essential because it has practical, real-world implications. During a crisis, ambiguity in legal frameworks can directly affect how nations respond. Well-structured provisions can help deter escalation; poorly drafted ones may create hesitation or uncertainty at pivotal moments. The team’s work focused on ensuring that the proposed language would withstand political pressure and operational realities.

Advancing peace through law

Our collaboration produced a comprehensive policy-planning paper offering both legal and practical guidance. This paper will inform ongoing diplomatic discussions and support the development of enforceable, realistic security arrangements for Ukraine.

The Firm’s ongoing partnership with PILPG on this and other rule-of-law initiatives highlights how global law firms can leverage their skills and resources to address significant international challenges, and advance peace and justice.

London partner Charles Balmain, who supervised the project, reflects: "While the war in Ukraine raises significant geopolitical issues, undertaking work that seeks legal pathways toward lasting peace is inherently apolitical and unquestionably constructive. It is precisely the type of pro bono project that global firms such as White & Case can—and should—be engaged in."

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Two satin fabrics, matching the blue and yellow colors of the Ukrainian flag.