In analyzing Russia’s invasion of Ukraine, many commentators have focused on factors specific to the actors in this case: President Vladimir Putin’s hatred of democracy, his desire to show that post-Soviet Russia remains a global power or Russians’ view that Ukraine is historically part of their state, to name a few examples. Putin has made his territorial ambitions in Ukraine abundantly clear — he seeks autonomy, at least, for the breakaway regions — and his motives are clearly nefarious. War, however, is not the obvious approach for achieving these goals. Why would Putin opt for a full-scale invasion instead of a diplomatic solution to the question of the disputed territories? What makes war attractive in this case is the fact that one country (Ukraine) has been positioning itself to join an alliance (NATO) meant to counter the other (Russia).
International-affairs scholars know that, throughout history, few moments are more ripe for war than when the enemy of one country makes a bid to join forces with other adversaries. Such alliances can utterly transform the balance of power between two countries, and therefore, when a potential alliance is signaled but not yet consummated, the nation that will be put at a disadvantage faces a huge incentive to strike.
Ukraine’s membership in NATO was hardly imminent, but Russia felt threatened enough by the possibility that it was willing to launch a war to prevent it (in addition to other nationalist goals Putin thinks he is achieving). Recognizing the dynamic at play is the first step toward understanding the conflict — and recognizing how NATO’s membership process may unintentionally invite this kind of crisis.
The relationship between alliance formation — imminent partnerships, especially — and war is a close one, as we explored in a recent scholarly article. In 1939, for instance, Britain made a commitment to defend Poland but was not able to make good on the pledge right away. Germany attacked Poland before Britain and France could get into position. In 1954, the Chinese communists attacked islands held by the Chinese nationalists in a failed attempt to block an alliance between the United States and Taiwan. And in a situation with marked parallels, albeit on a smaller scale, to the current crisis in Ukraine, Russia attacked Georgia in 2008 after NATO membership for that country was proposed. Perhaps not coincidentally, Georgia is still not a NATO member.
Alliances — even “defensive” ones such as NATO — bring about significant power shifts, creating a new strategic landscape. When a country stands to benefit from a future power shift caused by joining an alliance, then it knows its hand will be strengthened in future negotiations. After the power shift, it may be strong enough to flout agreements reached today. Its rival knows this as well. As a result, negotiations in the present — such as those that had been underway between Ukraine and Russia over the status of two breakaway regions in Ukraine’s east — lack staying power.
Political scientists refer to this phenomenon as a “commitment problem” — and commitment problems lead to crises and even war. Our research suggests that impending alliances are particularly dangerous when certain conditions apply: when the alliance explicitly or implicitly targets another country; when the anticipated power shift from the alliance is large; when it takes time for the alliance to be fully implemented (opening a window for attack); and when an attack is likely to block the alliance.
Ukraine potentially joining NATO checks those boxes. NATO is a military juggernaut, and Ukraine’s situation would be utterly transformed if its 30 members were pledged to defend it. NATO also “targets” Russia, in the sense that its raison d’etre, at its founding, was to counter the Soviet Union. In Putin’s mind, war today may lead to a better outcome than negotiating with Ukraine in the future, when it could be backed by the combined strength of NATO countries.
In principle, Ukraine and NATO might have defused the situation by committing to Ukraine being barred from NATO. But the underlying commitment problem, as well as other factors, made this approach unrealistic from the beginning. The NATO powers understandably didn’t want to reward Putin for his aggressive stance, which included massing troops on the border, and Ukraine wants badly to be under NATO’s umbrella. What’s more, it’s not clear that NATO’s rules permit such a concession: NATO’s “open door” policy, based on Article 10 of its founding treaty, holds out the promise of membership to any European country able to fulfill specific obligations of membership (civilian control of the military, a democratic government and so on). Why would Putin believe a commitment to rule out membership for Ukraine if it seems on track for meeting membership requirements?
Potential new alliances can often provoke hostility, but the path NATO lays out for potential members all but invites armed conflict — however inadvertently. To join NATO, countries must first be offered a membership action plan, which includes a formal invitation and a tailored road map for future membership. To obtain such a plan, prospective members must first peacefully resolve outstanding international, ethnic and territorial disputes. The problem this poses is obvious: Putin can sabotage a state’s NATO bid by starting a conflict.
He’s done it before. In 2004, new Georgian President Mikheil Saakashvili made accession to NATO a priority. Four years later at a NATO summit in Bucharest, Romania, President George W. Bush pushed for a membership action plan to be offered to Georgia. However, separatist movements in the Abkhazia and South Ossetia regions served as a roadblock. Other NATO members, including France and Germany, were reluctant to extend a membership action plan under these conditions.
Seeing an opportunity, Russia invaded in August 2008. (In 2011, Russian President Dmitry Medvedev boasted that Georgia would have already become a NATO member had Russia chosen not to attack.) Putin may have invaded the Crimean Peninsula in 2014, grabbing it from Ukraine, for similar reasons. By now, using force to thwart NATO bids is a standard play for Russia.
A better approach for defending Ukraine than the prospect of NATO membership might have used the United States’ commitment to Taiwan as a model. That commitment is deliberately ambiguous — and therefore sidesteps the problem of creating a dangerous implementation window on the way to a formal mutual defense pact. Certainly, the United States’ stance on Taiwan does not create a road map for China to use armed conflict to prevent a U.S.-Taiwan alliance, as the NATO membership rules do.
The invasion of Ukraine points to an underlying systemic problem. Telegraphing the possibility of a military commitment can trigger a dangerous race between efforts to implement and to block the alliance. NATO is likely to face these crises again, because its transparent and drawn-out membership processes exacerbate the dangers caused by potential alliances. Not every conflict will be as cataclysmic as the Ukraine invasion, but the negative incentive remains.
As the United States and its allies punish Russia with sanctions, and otherwise pressure Putin to withdraw from Ukraine, they should be thinking about how to change these structural flaws. In particular, the alliance might consider replacing its road map for future members with a more opaque, private, deliberative process, so that adversaries aren’t encouraged to preempt membership by instigating fights.
Feb. 24: This article has been updated.
An earlier version of this article stated incorrectly that Georgia's President Mikheil Saakashvili made NATO membership a priority beginning in 2003. He became president in January 2004. The article has been corrected.