NATO’s Eastward Expansion and the Geopolitical Consequences: From Enlargement to the Ukrainian War

Since 1999, Europe has never been the same. NATO’s first wave of enlargement after the Cold War, with Poland, Hungary, and the Czech Republic joining the Alliance, inaugurated a new era of security architecture in Europe. This was followed by the invitation of Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia, and Slovenia at the Prague Summit of 2002, and their formal admission in 2004—the largest enlargement in NATO’s history. Later waves brought Albania and Croatia (2009), Montenegro (2017), and North Macedonia (2020). Most recently, Finland joined in 2023, followed by Sweden in 2024.

This steady expansion has been portrayed as a triumph of integration and stability. Yet the process also laid the foundations for renewed confrontation. The 2008 Bucharest Summit offered a striking example. In its Declaration of 3 April 2008, NATO heads of state affirmed:

“NATO welcomes Ukraine’s and Georgia’s Euro-Atlantic aspirations for membership in NATO.  We agreed today that these countries will become
members of NATO.  Both nations have made valuable contributions to Alliance
operations.”¹

This promise, however, coincided with the brief but violent Russia–Georgia war of summer 2008 over Abkhazia and South Ossetia—a crisis that foreshadowed greater turbulence ahead.

Ukraine at the Crossroads

Ukraine’s strategic weight has long been evident. In 1991, it was the second-largest republic of the USSR and a major hub of its arms industry. By 1994, under U.S. pressure, Ukraine transferred its nuclear arsenal to Russia. President Bill Clinton assured President Kuchma in Washington that the United States “does not want to see Ukraine caught between NATO and Russia.” Yet that is precisely what unfolded.

Western policymakers faced a dilemma: would Ukraine’s integration with Western structures secure stability or merely deepen Russia’s insecurity? NATO’s expansion eastward, combined with the prospect of Ukrainian accession, created a dependency on Washington that Kyiv could hardly sustain without provoking Moscow.

Warnings from Within

As early as the mid-1990s, American analysts foresaw the risks. Arnold L. Horelick, National Intelligence Officer for the USSR at the CIA and later a RAND Corporation scholar, argued that NATO enlargement reflected a “paucity of other ideas” to revive a flagging alliance. Enlargement, he warned, might produce undesirable, unintended consequences that could outweigh the benefits.” The priority, Horelick insisted, should be fostering Russia’s democratic transformation rather than driving it toward revisionism and militarization.

Diplomatic cables from 1996 underscore this tension. U.S. Deputy Secretary of State meetings with Ukrainian officials revealed that Russia’s opposition to enlargement, while moderated by proposals of a NATO–Russia Charter, remained categorical on Ukraine and the Baltic states. Russian officials declared that their membership in NATO was unacceptable. Washington, however, conveyed to Moscow—and to European allies—that such conditions were “completely unacceptable.”

Analysts such as Alexei Pikayev of the Arbatov Institute warned that NATO enlargement in 1997, coinciding with the Alliance’s fiftieth anniversary, would appear as a deliberate provocation. From Moscow’s perspective, post–Cold War concessions had flowed only one way: German reunification, the independence of Poland, and the liberation of the Baltic states—all achieved without reciprocal guarantees.

Strategic Calculations: Kennan’s Prophetic Warning

American memoranda of the period emphasized consultation with Russia but denied it any veto over NATO decisions. For the first time, U.S. National Security Council documents highlighted that Ukraine and the Baltic states must not be consigned to a “gray zone” or “Russian sphere of influence.” This amounted to a form of neo-containment—articulated only rarely but ever present in Washington’s strategic calculations. The possibility of Russian accession to NATO, though not explicitly excluded, was implicitly ruled out. In effect, the Cold War’s spirit persisted beneath the surface of American policy.

Few voices were more eloquent than George Kennan, the architect of Cold War containment. Writing in 1997, Kennan condemned NATO enlargement as “the greatest mistake of Western policy in the entire post-Cold-War era.” He predicted that advancing NATO “smack up to those of Russia” would inflame nationalism, damage Russian democracy, restore a Cold War atmosphere, and spur an arms race—including renewed salience of nuclear weapons. Kennan’s warning soon appeared prescient. In March 1999, as NATO prepared to bomb Yugoslavia, Russian Prime Minister Yevgeny Primakov ordered his aircraft—en route to Washington—to turn back mid-Atlantic. This symbolic “U-turn” marked Russia’s turn toward multidimensional foreign policy and signaled the end of any illusion that Moscow would accept unilateral Western dominance.

From Enlargement to War

The war in Ukraine since 2014, and particularly after the Russian invasion of February 2022, stands as the most violent European crisis in decades. Contrary to media portrayals of sudden rupture, the conflict was long in gestation. NATO’s enlargement, combined with Ukraine’s ambiguous position between East and West, created the conditions for confrontation.

The geopolitical spark lay in the mismatch between Western ambitions and Russian insecurities. For Moscow, NATO expansion was nothing less than strategic encirclement; for Washington, it was the consolidation of a post-Cold War order. The result has been a clash that neither side considers accidental nor easily reversible.

Conclusion

The obsession with NATO’s eastward expansion cannot be explained solely by the triumphalist spirit of the post-1991 West. Rather, it reflects a deeper conviction within American strategic circles: that the Cold War never truly ended with the dissolution of the USSR. As Kennan had already warned decades earlier, attempts to project NATO’s borders up to Russia’s doorstep risked destabilizing Europe’s fragile security order. Today, with the war in Ukraine ongoing and the nuclear shadow looming once more, the debates of the 1990s appear less like historical controversies than like unheeded warnings. Enlargement, once celebrated as a symbol of unity, has become the trigger of
Europe’s most dangerous conflict since 1945.

Published by Diplomatic Front — YouTube channel & editorial platform for strategic and geopolitical analysis.
Editor: Diplomatic Front

---

¹ https://www.nato.int/cps/en/natohq/official_texts_8443.htm