Proponents of NATO expansion hold that enlarging the Alliance is a legitimate exercise of sovereign nations' right to choose their own security arrangements, that expansion has contributed to stability and democracy in Europe, and that Russian objections to enlargement reflect imperial ambitions rather than genuine defensive concerns. This view is held across a wide spectrum - liberal internationalists, neoconservatives, Eastern European nationalists, and realist-leaning security scholars who emphasize deterrence. It is the prevailing position among Western foreign policy establishments and the governments of NATO member states.

Expansion advocates argue that the foundational premise of international order is that independent states may freely choose their alliances. The 1975 Helsinki Final Act, to which the Soviet Union was a signatory, explicitly affirmed each state's right to choose or change its security arrangements. Proponents contend that accepting a Russian veto over neighboring countries' alliance membership would establish a hierarchical international system in which great powers hold permanent dominion over smaller neighbors - precisely the arrangement NATO was created to prevent.

Article 10 of the North Atlantic Treaty provides that any European state “in a position to further the principles of this Treaty” may be invited to accede. Advocates argue this is not an aggressive posture but a standing offer. No state has been compelled to join; each accession has followed domestic political processes and formal application. From this perspective, framing enlargement as Western aggression inverts the actual causal sequence: countries sought membership because they perceived threats, and the Alliance responded to applications.

Proponents point to the post-Cold War record of Eastern Europe as evidence that NATO integration correlates with democratic consolidation, civilian control of militaries, and resolution of ethnic and border conflicts. The Baltic states, Poland, and the Czech Republic underwent substantial institutional reforms as conditions of accession. Expansion advocates argue that far from destabilizing Europe, enlargement extended a zone of peace that had previously been confined to Western Europe.

A strand of pro-expansion argument rests on straightforward deterrence theory. States that joined NATO - the Baltic states, Poland, Romania - have not been invaded. States that did not join or were blocked from joining - Georgia and Ukraine - have been subject to Russian military action. Advocates argue this contrast is not coincidental and vindicates the deterrence rationale for expansion rather than undermining it.

Expansion proponents dispute the argument that the West broke a promise not to expand NATO eastward. They note that no such commitment was made in any binding treaty. The most that can be documented, they argue, are informal statements made during reunification negotiations in 1990 - before Eastern European countries were independent actors seeking membership, and before the Soviet Union itself had dissolved. The claim of a broken promise, in this view, is Russian revisionism rather than historical fact, a position supported by the documentary record examined by scholars including Mark Kramer and Mary Elise Sarotte, who disagree about context but agree no formal commitment was made.¹⁾²⁾

Following Russia's annexation of Crimea in 2014 and full-scale invasion of Ukraine in 2022, expansion advocates argue that Eastern European anxieties about Russian intentions have been thoroughly vindicated. Countries that pressed hardest for NATO membership - Poland and the Baltic states in particular - are seen as having understood the security environment more clearly than Western European states that counseled accommodation. The argument that expansion provoked Russian aggression is, in this view, refuted by the fact that Russia attacked a country that had not joined NATO and had been explicitly told it would not receive a membership action plan in the near term.

The pro-expansion consensus emerged gradually after the Cold War. The Clinton administration was initially cautious, aware of Russian sensitivities, but by the mid-1990s Eastern European lobbying, bipartisan congressional pressure, and the logic of rewarding democratic transitions shifted the policy. The 1997 Madrid Summit invited Poland, Hungary, and the Czech Republic; the 2004 “big bang” enlargement brought in seven states including the three Baltic republics, the most geopolitically significant expansion given their former status as Soviet territory.

The 2008 Bucharest Summit declaration that Ukraine and Georgia “will become members” - without offering a Membership Action Plan - is viewed by expansion advocates as an unfortunate compromise: alarming Russia without providing the security guarantee that would have deterred Russian adventurism. Some proponents argue Bucharest represented not too much expansion but too little follow-through.

Finland and Sweden's accession in 2023-2024, prompted by Russia's invasion of Ukraine, is seen by proponents as the clearest possible validation of the open-door principle: two long-neutral democracies concluded, on their own, that Alliance membership was necessary for their security. Finland joined as the 31st ally in April 2023; Sweden joined as the 32nd ally in March 2024.³⁾⁴⁾

Zbigniew Brzezinski (1928-2017) - National Security Advisor under Carter and one of the intellectual architects of post-Cold War NATO policy. His 1997 The Grand Chessboard argued that consolidating Western influence in Eastern Europe was essential to preventing a re-emergence of Russian imperialism.⁵⁾

Madeleine Albright (1937-2022) - Secretary of State during the first round of post-Cold War enlargement. Albright argued consistently that expansion rewarded democratic reform and that Russian objections reflected a desire to maintain a sphere of domination rather than legitimate security interests.

M.E. Sarotte - Historian at Johns Hopkins SAIS whose detailed archival work on the 1990 negotiations is used by expansion advocates to rebut the broken-promises thesis, even as Sarotte herself notes the ambiguity of statements made at the time.

Anne Applebaum - Journalist and historian whose work on Eastern Europe and Soviet history informs the view that Russian imperialism is a structural feature of the state rather than a reaction to NATO provocation. Her writings argue that accommodation of Russian demands has historically encouraged further aggression.⁶⁾

Toomas Hendrik Ilves - Former President of Estonia and a prominent voice for the view, common among Eastern European leaders, that Western skepticism of expansion reflects a failure to understand Russian foreign policy as Eastern Europeans have experienced it.

Victoria Nuland - Former Under Secretary of State for Political Affairs, a persistent advocate of Ukrainian Euro-Atlantic integration and an institutionalist proponent of the expansion project.

Proponents of expansion are not unified on every question.

Pace and sequencing - Some advocates argue the West was too cautious and slow, leaving a window of vulnerability for states between NATO's eastern border and Russia. Others - including some who support expansion in principle - argue the 2008 Bucharest declaration was reckless because it offered aspiration without protection.

Ukraine and Georgia - A subset of expansion proponents supports eventual Ukrainian and Georgian membership as a matter of right and strategic logic. Others, including some who supported all previous rounds of enlargement, argue that admitting states with unresolved territorial conflicts or active wars poses distinct problems for Alliance cohesion and Article 5 credibility.

Conditionality - Some advocates argue that post-2004 expansions moved too quickly and admitted states that had not fully met democratic and rule-of-law criteria, weakening the normative case for enlargement. Hungary's subsequent democratic backsliding is often cited.

Relationship to EU enlargement - Some proponents argue NATO and EU expansion should be treated as a single project of Western integration; others see the two institutions as having distinct logics that should not be conflated.

• NATO
• NATO History
• NATO Expansion
• NATO Expansion Debate
• NATO Expansion - Opposition Viewpoint
• NATO Expansion - Realist Opposition Viewpoint
• NATO Expansion - No-Promises Debate
• Russia-Ukraine War
• Russia-Ukraine War Debate
• NATO Security Consensus

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