Editor’s Note: This article is part 2 in a 2-part series looking at the various forms of neutrality in international law and how they should be updated in the aftermath of the Ukraine crisis. 

In the immediate aftermath of Russia’s unprovoked invasion of Ukraine, some observers speculated that Kyiv could agree to terms of “neutralization” as part of a peace agreement. That notion, however, has been discarded in the intervening months, as Russia’s brutality and war crimes have led to both Ukraine and the international community hardening their stance on the contours of a peace agreement. Sweden and Finland have even decided to abandon their decades of neutrality and applied to join NATO. Will the Russia-Ukraine war be the death knell of neutralization?

President Joe Biden, center, with President Sauli Niinistö of Finland, left, and Prime Minister Magdalena Andersson of Sweden deliver remarks in the Rose Garden of the White House in Washington, May 19, 2022. (Sarah Silbiger/The New York Times)
President Joe Biden, center, with President Sauli Niinistö of Finland, left, and Prime Minister Magdalena Andersson of Sweden deliver remarks in the Rose Garden of the White House in Washington, May 19, 2022. (Sarah Silbiger/The New York Times)

This analysis — Part 2 of a USIP series exploring concepts of neutrality and what they could look like after the Russia-Ukraine war — examines the historical and legal complexity of “neutralization” or “permanent neutrality” by international agreement. (Part one of this series discussed the “law of neutrality,” referring to the rights and obligations of neutral states and citizens following the outbreak of international armed conflict.)


The concept of neutralization, as it exists today, was broadly summarized by Cyrus French Wicker in 1910:

“Neutralization is the imposition by international agreement of perpetual neutrality over land and water. Its purpose is the removal of objects of international dispute by placing them forever outside of the realm of war, which is lessened by their extent.”

Wicker’s modern legal concept of neutralization took shape following the Napoleonic wars, when the representatives of major powers worked to establish stability across Europe. Most famously, Swiss neutrality was a long time in the making. Its internationally obligated restraint started in the aftermath of the battle of Marignano in 1515 when Switzerland signed a treaty committing to never take arms against the French. It was however, a series of international agreements and other legal instruments, including the Final Act of the Congress of Vienna and the Second Treaty of Paris in 1815, which provided the complex commercial and security arrangements for individual cantons and Switzerland’s neutralization more broadly.

Of specific importance from that era is the Final Act of the Vienna Congress, which provided straightforward terms for the neutralization of Cracow, Poland. The relevant provisions stated that, “The town of Cracow, with its territory, is declared to be for ever [sic] a free, independent, and strictly neutral city, under the protection of Austria, Russia, and Prussia.” The agreements went on to declare, “no military establishment shall be formed that can menace the neutrality of Cracow.” These terms are indicative of the core issues at play when negotiating neutralization: the guarantees and guarantors of security for the neutral territory, and the restrictions and obligations of those governing the neutral territory.

On its face, neutralization appears in stark contrast to membership in a powerful security alliance. However, much can be learned from the North Atlantic Treaty that formed NATO.

For starters, it is crucial for peace agreements, as legal instruments, to have operational components that galvanize cooperation. Similarly, at their heart, security alliances are binding collective defense obligations, as exhibited by Article 5 of the NATO Treaty and Article 4 of the Russian-led Collective Security Treaty Organization.

It was Germany’s violation of Belgium’s neutralization in 1914 that triggered Great Britain to uphold its security guarantees under the Treaty of London of 1839. There are several parallels with the World War I German invasion of Belgium that parallel with conflict in Ukraine today. Like Russia, Germany also lost the public opinion by waging a brutal war and killing thousands of Belgian civilians. Belgium put up a strong fight, holding onto a corner of the country all the way until the 1918 Armistice. It was this brave resistance that secured a crucial link for communications and supply lines for the Allied Powers.

What Territories have Been Neutralized — and Why?

What leads countries to agree to neutralization? And how should the international legal mechanisms work?  

Since the 19th century, neutralization has been a cooperative legal tool deployed by major powers to govern strategic interests in would-be disputed territories, including bodies of water. For centuries, Switzerland’s centrality and mountainous terrain made it a ripe location for great power rivalry between France, Germany and Italy. In 1830, Belgium was created as an independent, neutralized nation to serve as a buffer between France and Germany. And it was the Treaty of Paris in 1856 that neutralized the Black Sea. Of course, neutralization was also used as part of the reprehensible division of colonial territories, as we saw in the case of the Congo Basin, by the terms of Chapter Three of the Act of the Conference of Berlin.  

It's clear that neutralization has been a tool used to mediate the geographically driven strategic and economic interests of great powers. It has been argued that the strategic disputes over Ukraine harken back to Sir Halford Mackinder’s “Heartland Theory” of 1904. In his model, Ukraine is pivotal to controlling the “Heartland.” In a concept that would later inspire the Nazis as well as Putin’s right-wing nationalist base, he famously stated: “Who rules East Europe commands the Heartland; Who rules the Heartland commands the World Island [Eurasia and Africa]; Who rules the World Island commands the World.”

As the forerunner for “geopolitical theory,” Mackinder’s work has been heavily criticized as reductionist, determinist and an anachronistic relic of the colonial era. That said, it is useful for understanding the sort of strategic factors historically considered among the great powers when negotiating the terms of neutralization.

With the fall of the Soviet Union, the United States emerged as the great power in a new “unipolar” world. This was the context in which Ukraine’s security status was discussed in 1994. At that time, external concerns over Ukraine’s security status had much to do with its possession of nuclear weapons, and its proximity to Russia.

Legal Considerations

For its part, Ukraine was seeking the type of robust guarantees and protections provided to Belgium in 1830 when Ukraine voluntarily gave up the world’s third largest stockpile of nuclear weapons and signed what became known as the Budapest Memorandum in 1994, part of the negotiations for its accession to the Treaty on Non-Proliferation of Nuclear Weapons. The memorandum was also signed by Russia, the United States and the United Kingdom and was later supported by France and China. It provided commitments by the parties to help protect Ukraine’s territorial integrity — specifically, signatories gave “assurances” that any acts of aggression would be brought immediately to the U.N. Security Council.  

These security “assurances” mostly restated commitments in the U.N. Charter, which themselves are part of customary international law. But at the time, as it considered giving up its nuclear weapons, Ukraine was looking for security guarantees beyond accepted custom and sought legal commitments through a binding treaty.

In 2010, Ukraine’s parliament passed a law stipulating the country’s non-aligned status. But Ukraine’s neutrality did not stop Russia from invading in 2014. Indeed, it made it easier.

The strength of the commitments to Ukraine included in the Budapest Memorandum were tested in 2014 with Russia’s invasion of Crimea and eastern Ukraine. Despite the assurances, the United States asserted that it did not consider the memorandum a legal agreement requiring direct military intervention, but rather it was a statement of political intent. However, prominent international law professor Steven Blockmans has said that “in spite of what its name suggests, the memorandum qualifies as an international agreement under the terms of the 1969 Vienna Convention on the Law of Treaties.”

All of the law at issue is captured in the 1969 Vienna Convention on the Law of Treaties, which served to codify accepted customary international law — and in the context of this discussion on neutralization, it appears that the Budapest Memorandum meets the basic requirements of a binding treaty. Of note is the fact that it was a written agreement signed by the heads of state, including then-President Bill Clinton, and was registered with the U.N. as a multilateral treaty.

Much has also been made of the term “security assurances” in the memorandum versus “security guarantees.” In international law, the word itself is of no consequence, except as it pertains to an interpretation of the reasonable determination of the intent to be bound. There is significant evidence that the United States signaled its intentions to only provide Ukraine with political assurances, and the memorandum was not intended to be a legal treaty.

The determination of intent, in large part is determined by the travaux préparatoires, or the documentary evidence of the negotiation, discussions and drafting of a final text. The Vienna Convention’s official commentary recognizes that jurists differ in their approach to the interpretation of treaties.

As held by the International Court of Justice in the cases of Qatar v. Bahrain (2001) and Argentina v. Uruguay (2010), what matters is the whole of the evidence to the effect of an intention by the parties to be bound with legal effect. That said, a “plurilateral agreement” like the Budapest Memorandum is a type of multilateral agreement with a limited number of parties — in this case depositories of the non-proliferation treaty and permanent members of the U.N. Security Council. The interpretation of one party’s intent is less supportive in a multilateral treaty.

Finally, the Budapest Memorandum was not ratified. The United States president may ratify international treaties, as a matter of constitutional law, with the advice and consent of two-thirds of the Senate. This is not the only way international agreements become binding. Executive agreements, without the Senates’ approval, can still be binding on the parties under international law. Famously, in 1918 the Lansing-Ishii Agreement, was said to have no legal force. However, it took a formal conference in 1921, two treaties, and an exchange of notes to expunge this “Gentlemen’s Agreement,” which was only permanently ended after 17 years by an act of Congress.

The good-faith negotiation and fulfillment of international commitments have real implications on the long-term prosperity and national security of the United States. Ignoring such obligations damages the United States’ ability to form important strategic alliances. In support of any potential future peace agreement between Ukraine and Russia, the United States may want to ensure that its political objectives follow a principled approach.

Engaging in Good Faith

International relations theories have explored the extent to which “trust,” at the individual and institutional levels, contributes to the functioning or disruptions of the global order. Scholar Aaron Hoffman has posited that confidence to put trust in others requires taking the risk that the other party will “do what is right.” This requires good faith engagements, where possible.

Experiences with the Budapest Memorandum will likely inform Ukraine’s way forward. Central to the considerations may be the treaty law principle of pacta sunt servanda — embodied in Article 26 of the Vienna Convention — which states that “every treaty in force is binding upon the parties to it and must be performed in good faith.”

Of course, the most extraordinary hurdle will be ensuring Ukrainians of Russia’s credibility. For his part, Putin has been clear about this point, saying in 2015 following the initial outbreak of conflict with Ukraine, “What has trust got to do with it? This is not about trust — it is about having our interests taken into consideration.”

In the context of ending the war, this means trustworthy security guarantees from international partners will be more important than ever to counter Russia’s cynical disregard for international legal norms.

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