BRUSSELS, July 8 — NATO has undergone nine rounds of enlargement since the alliance was founded in 1949, according to the official record of member-state accessions. The expansion, which brings the alliance to 32 members, follows a process governed by Article 10 of the North Atlantic Treaty, which allows any European state to join if it meets criteria including a functioning democratic political system, a market economy, and a commitment to shared values. The latest round of enlargement continues a pattern that began after the Cold War.
The first post-Cold War enlargement occurred in 1999, when the Czech Republic, Hungary, and Poland joined. Subsequent rounds added Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia, and Slovenia in 2004.
Albania and Croatia joined in 2009, followed by Montenegro in 2017 and North Macedonia in 2020. Finland became the 31st member on April 4, 2023, abandoning decades of military non-alignment after Russia’s 2022 invasion of Ukraine. That decision, officials confirmed, marked a significant shift in European security architecture.
Sweden applied for membership in May 2022 and, as of 2023, awaited ratification from Hungary and Turkey.
Strategic Context and Russian Response
The enlargement process has long been a point of contention between NATO and Russia. The 1997 NATO-Russia Founding Act, which established a joint council for consultation and cooperation, was suspended by NATO in April 2014 after Russia’s annexation of Crimea. The record shows that this suspension effectively ended the formal mechanism for dialogue between the alliance and Moscow.
Russian officials have consistently characterized NATO enlargement as a threat to their national security. According to statements from the Kremlin, each round of expansion moves military infrastructure closer to Russian borders.
The accession of Finland, which shares a border with Russia, has been described by Russian officials as a particularly significant development.
Membership Criteria and Process
The enlargement process is governed by Article 10 of the North Atlantic Treaty, which allows any European state to join if it meets specific criteria. These criteria include a functioning democratic political system, a market economy, and a commitment to shared values. The alliance also requires candidate countries to demonstrate their ability to contribute to collective defense.
The process typically involves multiple stages, including political dialogue, membership action plans, and accession protocols. Each existing member state must ratify the accession of new members through its own national procedures.
This requirement has sometimes created delays, as seen in the cases of Hungary and Turkey regarding Sweden’s application.
Looking Ahead
The expansion of NATO continues to reshape European security dynamics. As of 2023, the alliance faces questions about further enlargement, the status of pending applications, and the long-term implications of Russia’s war in Ukraine. The suspension of the NATO-Russia Founding Act remains in effect, with no formal mechanism for dialogue between the alliance and Moscow.
The record shows that NATO’s enlargement has been a consistent feature of post-Cold War European security, with each round bringing new members and new strategic calculations. The coming months will likely see continued debate about the pace and scope of further expansion, as well as the alliance’s relationship with Russia.
