Did NATO's expansions drive Vladimir Putin to war?

The combination of Russia's decades-old fear of an eastwards-expanding NATO and its own invasion into Ukraine seems to have had an adverse effect: non-aligned Finland and Sweden strongly considering joining the anti-Russian alliance and increasing the tense stand-off between Moscow and the west. 

"A sort of 'neo-isolation' is how the Russian public sees NATO's eastward expansion." At least, in the opinion of Russian President Boris Yeltsin, who wrote a long letter to his US counterpart, "Dear Bill" Clinton in 1993, when it became clear that some of the former satellite states of the USSR wanted to swap sides.

Yeltsin wrote after former Warsaw-pact countries Poland, Hungary and the Czech Republic had expressed interest in joining the alliance.

"Of course," he wrote, "every country can decide its allegiance," but that would go against the "Two Plus Four Treaty" (between East and West Germany, France, the UK, the US and the USSR) that led to Germany's reunification in 1990, which, Yeltsin said, "precluded the option of expanding the NATO zone into the east."

But the Two Plus Four Treaty says no such thing. It does state that "the right of the united Germany to belong to alliances shall not be affected by the present Treaty." In practice this meant that former Warsaw Pact member East Germany - now merged with NATO member West Germany, would be part of the alliance as well. But the treaty did not say a word about other former Warsaw Pact countries joining NATO.

In fact, the often-cited promise that NATO would not expand to the east was never signed into any treaty. But some of the wording uttered by American negotiators was, intentionally or not, vague.

Probably most used by Moscow's propaganda is a quotation by US Secretary of State James Baker who said, during a meeting with the USSR's last leader Michael Gorbachev in February 1990, three months after the fall of the Berlin Wall, that "there would be no extension of NATO's jurisdiction for forces of NATO one inch to the east." 

According to minutes of a meeting between then President Yeltsin and US Secretary of State Warren Christopher on 22 October 1993 in Moscow - which took place after Yeltsin's "Dear Bill" letter and released to the public under the Freedom of Information Act, Christopher said that Russia would not be "ignored or excluded from full participation in the future security of Europe" but integrated in a "Partnership for Peace" which would put Russia and other newly independent former Soviet republics ("NIS") on an equal footing with NATO. 

According to the account, Yeltsin was enthusiastic and said that the idea "serves to dissipate all of the tension which we now have in Russia regarding East European states and their aspirations with respect to NATO ... now we are all equal and it will ensure equal participation on the basis of partnership." Problem solved, no eastward expansion?

The opposite happened. In five waves, starting in 1999, NATO did expand eastward, eagerly incorporating all former Warsaw Pact countries except Russia itself. In 1999, Poland, Hungary and the Czech Republic joined.

Biggest expansion
In 2004, four years after Yeltsin gave over Russia's presidential reins to Vladimir Putin, NATO saw the biggest expansion since its founding in 1949 with Bulgaria, Romania, Slovakia, Slovenia and the three Baltic states - Estonia, Latvia and Lithuania - joining.

The first four were former Warsaw Pact states. But what made Putin particularly angry was that the Baltic states belonged to the USSR itself.

Relations between Putin and the NATO countries was initially courteous: the NATO-Russia Council (NRC) was established, Russia and the alliance engaged in joint military exercises, and Russia's membership expanded the G7 into the G8.

In his speech to the German Bundestag in 2001, in fluent German, Putin stated that Russia's "heart was open to true cooperation and partnership" with the west.

But that came after he had spoken out against NATO's first post-cold-war expansion two years earlier. 

Six years later, his tone had hardened considerably. Most of the former Warsaw Pact was now integrated into NATO and Putin's 2007 speech in Munich (in Russian) marked a turning point.

He scolded NATO for having "put its frontline forces on our borders," adding that the expansion "does not have any relation with the modernisation of the aalliance itself or with ensuring security in Europe."

He branded it a "serious provocation that reduces the level of mutual trust." Washington and its NATO partners hardly took notice of the implicit warning. 

Things escalated when former Soviet Union republics Georgia and Ukraine started to show interest in a possible NATO membership.

But increased Russian aggression against Georgia (invasion in 2008) and Ukraine (annexation of Crimea in 2014) possibly made NATO partners hesitate to ever seriously consider membership: the alliance's "collective defence" Article 5 stipulates that "an attack on one of the members means an attack on all" and would immediately pull the alliance into a direct confrontation with Moscow. 

Finland and Sweden
But the entry of Russian armed forces into Ukraine in February 2022 and the ensuing conflct triggered two formerly non-aligned countries, Finland and Sweden, into weighing up whether to become NATO members.

It may become the quickest NATO enlargement and one that would redraw Europe's security map. 

Should they apply for membership, the move would have far-reaching ramifications for northern Europe and trans-Atlantic security.

This will undoubtedly anger Moscow, which blames, at least in part, its war in Ukraine on NATO's continued expansion closer to its borders.

It is unclear how Putin might retaliate. The Kremlin said on Thursday that it certainly will not improve European security.

• Finland wants to join NATO 'without delay' in major policy shift