Is NATO Expansion the Real Cause of the Ukraine War?

In this interview, Russian President Vladimir Putin explicitly frames the 2022 invasion of Ukraine as a necessary response to NATO's eastward expansion, which he claims violated informal assurances given to Soviet leader Mikhail Gorbachev in 1990. He cites the alliance's 1999 bombing of Yugoslavia, its 2004 enlargement to include the Baltics, and the ongoing 'development of the territory of Ukraine' as proof of a broken promise and a direct security threat to Russia's 'existential' interests. Putin argues that the West's refusal to consider Russia's red lines forced Moscow to act preemptively to protect its sovereignty.

This academic analysis details the 2008 NATO Bucharest summit declaration, which stated that Ukraine and Georgia 'will become members of NATO,' despite strong opposition from key European allies like rance and Germany. The paper argues that this declaration, coupled with the subsequent refusal to provide a Membership Action Plan, created a 'grey zone' of ambiguous security guarantees that heightened Russia's security dilemma. It cites declassified diplomatic cables showing that U.S. officials deliberately pushed the language to provoke a reaction from Moscow, which they anticipated, and that Russia's 2014 annexation of Crimea can be directly traced to this 'provocative and ill-defined' policy.

This piece by former NATO Secretary General Jens Stoltenberg argues that Russia's invasion of Ukraine is a war of choice, not a response to NATO expansion. He emphasizes that NATO is a defensive alliance that has never attacked Russia, and that every enlargement since 1999 was a voluntary act by sovereign states fleeing Soviet-era oppression. Stoltenberg points to the 2022 invasion of a non-NATO member as definitive proof that the alliance's growth is a pretext, not a cause—if NATO were the issue, Russia would have invaded Poland or the Baltics. He also dismisses the '1990 promise' as a myth, noting that no treaty was signed and that the verbal assurances were specific to East Germany.

This detailed report from the RAND Corporation, a U.S. defense think tank, analyzes the Kremlin's own decision-making documents and public statements to conclude that the invasion was driven by a desire to restore imperial control over Ukraine, not by a defensive reaction to NATO. It highlights that Russia's original war plans called for the decapitation of the Ukrainian government and the installation of a puppet regime, with no mention of NATO bases as military targets. The report also notes that Russia has historically used the 'NATO threat' narrative to justify interventions in Georgia (2008) and Syria (2015), where NATO had no presence, suggesting the framing is a consistent tool for imperial aggression rather than a genuine security calculus.