For 20 years, NATO and European security policy have been guided by four flawed strategic assumptions. First, Western leaders assumed that Russia had become a benign power and that inter-state threats to European security were therefore no longer a concern. Second, because NATO’s core mission -- collective defense -- was no longer a compelling reason to keep the alliance together, leaders argued that NATO needed to go “out of area or out of business.” NATO consequently expanded its membership and took on a new array of global missions. Third, Western leaders assumed that NATO expansion would not provoke a reaction from Russia. NATO’s leaders believed their own rhetoric about the benign nature of NATO expansion, and they assumed Moscow would see it this way as well. Fourth, they believed that the alliance would be successful in carrying out military and stabilization missions in far-off places such as Afghanistan, Iraq, and Libya.

In 2014, Western officials are learning about their strategic errors the hard way. They have come to realize that NATO’s collective defense mission in Europe is still vital because Russia is in the business of changing international borders by force, that NATO never had to go “out of area” for a compelling mission, that the Kremlin didn’t see NATO expansion to Russia’s borders as benign, and that NATO missions in Afghanistan, Iraq, and Libya cost a great deal in lives and money but they only achieved mixed results.

As U.S. and European officials scramble to devise a coherent, credible, effective response to Russian aggression in Ukraine, they must also undertake a fundamental strategic reassessment. Europe still faces inter-state security threats, in the form of Russian aggression. NATO’s core mission -- collective defense -- is still vital. Deterrence and defense are still needed in Europe. And, as in many great-power relationships, the challenge is to deter aggression and reassure allies without provoking escalation.

For U.S. and European leaders -- and for NATO -- it’s back to basics.

OUT OF AREA, OUT OF WHACK

Following the collapse of Soviet power in Eastern Europe in 1989 and the break-up of the Soviet Union itself in 1991, it was natural and inevitable that NATO would change. The alliance had been created to deter -- and, if necessary, defend against -- a Soviet attack on Western Europe. With the Soviet Union gone, the military balance in Europe suddenly and fundamentally shifted. NATO’s raison d’être was called into question.

By the mid-1990s, the conventional wisdom was that NATO must go “out of area or out of business.” This view was promulgated by most (but not all) security policy experts, and it was ultimately embraced by the alliance’s leadership. This led to two main changes in NATO policy.

First, the leadership expanded the alliance from 16 to 28 members, bringing in countries from the former Warsaw Pact and the former Soviet Union, in particular. In 1999, the Czech Republic, Hungary, and Poland formally joined NATO. In 2004, Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia, and Slovenia joined the alliance. Albania and Croatia became NATO members in 2009.

In the 1990s, some scholars and commentators -- including me -- argued that NATO expansion could be counter-productive because it could trigger a backlash in Russia. NATO expansion could give Russian nationalists and political opportunists yet another weapon to use against pro-Western factions in Russia’s domestic political arena. In the worst-case scenario, embittered nationalists or opportunists could come to power and adopt more aggressive policies toward Europe and the United States. “The emergence of a kinder, gentler Russia is far from certain,” I wrote at the time, “but it is not in the interests of the United States or NATO’s European members to take steps that would make Russian authoritarianism and belligerence more likely.”

U.S. and European leaders preferred to believe that their intentions were benign and that Russia’s leaders would see NATO expansion in that benign light. The alliance’s leaders also believed that their diplomatic overtures to Russia -- such as the creation of a NATO-Russia Permanent Joint Council in 1997 -- would further pacify the Kremlin. That was wishful thinking.

In a recent Washington Post article, Jack F. Matlock, the former U.S. ambassador to Moscow, observed that the effect of NATO actions in the 1990s -- alliance expansion and the bombing of Serbia in 1999 without UN Security Council authorization -- was “devastating.” He observed that in 1991, Russian public opinion polls indicated that approximately 80 percent of Russian citizens had a positive view of the United States; in 1999, nearly the same number had a negative view of the country. In 2000, Vladimir Putin was elected president of the Russian Federation.

The second major change in NATO policy, starting in the 1990s, was the adoption of a new array of global missions to justify NATO’s continued existence. The rationale was that NATO’s European members would have to help Washington with its global concerns to keep the United States committed to Europe.

This strategic reasoning was based on several flawed assumptions. First, the global interests of the United States and Europe were not (and are not) in alignment. Second, Europe had limited power-projection capabilities in the 1990s, and these capabilities declined substantially over time. Third, the far-flung security problems that would be tackled -- Afghanistan, Iraq, Libya -- were exceptionally formidable. Success, which would depend on high levels of political will and material commitments sustained over time, would be difficult to achieve.

As he was about to step down as U.S. Secretary of Defense in June 2011, Robert Gates assessed the track record. In Afghanistan, he said in a 2011 speech, the “mission has exposed significant shortcomings in NATO -- in military capabilities and in political will. Despite more than 2 million troops in uniform -- NOT counting the U.S. military -- NATO has struggled, at times desperately, to sustain a deployment of 25-40,000 troops.” In Libya, he continued, “it has become painfully clear that similar shortcomings -- in capability and will -- have the potential to jeopardize the alliance’s ability to conduct an integrated, effective and sustained air-sea campaign.... [While] every alliance member voted for the Libya mission, less than half have participated at all, and fewer than a third have been willing to participate in the strike mission.”

“Going global” did not make NATO more relevant, effective, or credible. To the contrary, these operations entailed tremendous costs -- in terms of lives, money, political unity, and alliance credibility. These operations also drained European military capabilities that were already weak and are now even more steeply in decline. Expectations have been dashed, and the alliance’s credibility has been damaged.

Unfortunately, this has happened just as security threats in Europe have reemerged, in ways that are now obvious to almost everyone. Ironically, these threats have developed in part because of NATO’s own misguided actions.

GRAVE NEW WORLD

U.S. and European leaders are now grappling with the immediate challenge posed by Russia’s aggression in Ukraine, but they must also undertake a fundamental strategic reassessment.

First, they must recognize that Europe still faces inter-state security threats. For decades, Americans and western Europeans believed that inter-state war in Europe was unthinkable; they were confident in the emergence of a Europe that was “whole, free, and at peace.” They believed that Russia would behave as if it were a member of the NATO-EU club, even though there was no chance that it would be admitted to the club any time soon.

Putin has chosen another path. Russian aggression is real, and it may continue. Putin’s, domestic approval ratings are up, and they may stay up unless economic sanctions change Russian public and elite opinion. Putin is not yet looking for an “off-ramp” to defuse the confrontation. To the contrary, he currently has a domestic political incentive for a sustained confrontation with the West.

As President Toomas Hendrik Ilves of Estonia recently observed: “The fundamental understanding of security in Europe has now collapsed. Everything that has happened since 1989 has been predicted on the fundamental assumption that you don’t change borders by force, and that’s now out the window.” General Philip Breedlove, NATO’s Supreme Allied Commander Europe, put it succinctly, “It’s a paradigm shift.”

Second, U.S. and European leaders will have to devise new security responses to counter Russia’s new, semi-covert forms of military aggression. Russia’s campaigns in Crimea and eastern Ukraine have not involved columns of tanks streaming across borders. Instead, Moscow has skillfully used staged provocations, local supporters, unmarked special forces, cyber-attacks, and massive disinformation campaigns to create instabilities that can be used as pretexts for annexation.

To date, the U.S. and European responses have been very modest and almost entirely traditional in character -- verbal assurances; some small, additional troop rotations in eastern Europe; and some small, additional military exercises. NATO needs to think hard and fast about countering Russia’s new form of warfare, especially for NATO members that have Russian minorities. This will entail substantially enhanced internal security, homeland security, training, intelligence, early warning, cybersecurity, and public diplomacy capacities. These will be the keys to deterrence and defense against destabilization operations.

Third, U.S. and European leaders will have to forge a consensus on broader, long-term responses to Russia. Many Europeans are still in denial, and Europe is therefore divided. Belief systems are notoriously resistant to change, and the appeal of a European security nirvana was especially powerful.

Europe’s paralysis is reinforced by economic vulnerabilities (many European countries depend on Russian energy experts) and other economic and business ties with Russia. As a result, there is a range of opinion in Europe on Russia, and it varies according to geography, of course. Countries that are closer to Russia -- Poland and the Baltic states, in particular -- are afraid of Russia and have called for strong Western responses. Bridging these intra-European differences will not be easy.

To forge a consensus, U.S. and European leaders will have to reduce Europe’s dependence on Russia’s energy exports. These vulnerabilities make it difficult for many western European countries to contemplate strong responses to Russia’s aggression. Russia’s energy leverage makes Russian aggression more likely to continue. Reducing Europe’s energy vulnerabilities and simultaneously undercutting Russia’s energy and economic position will reinforce deterrence and stability in Europe.

Fourth, U.S. and European leaders should also re-double their efforts to complete the Transatlantic Trade and Investment Partnership (T-TIP), a new U.S.-EU trade agreement. The initial impetus for T-TIP was to give the U.S. and European economies a boost and strengthen their economic ties in the face of a rising China. Completion of the agreement would now have added benefits -- economic, political, and symbolic -- with respect to Russia. It may be difficult to complete a deal prior to the U.S. elections in November 2014. If that proves to be the case, T-TIP should be a top priority in 2015.

Fifth and last, U.S. and European leaders will of course have to continue to engage Putin and Russia. Currently, it appears that Putin has an expansionist agenda: bringing Russian-speakers into the Russian federation (even if they currently live in contiguous, sovereign states); establishing a Russian sphere of influence in Eastern Europe, the Caucasus, and Central Asia; redrawing international borders where possible; maintaining a state of confrontation with the West, which has strengthened his domestic position; and perhaps breaking up NATO itself. It would be a mistake to underestimate Putin’s aspirations and the nature of the threat. Western leaders will have to determine Putin’s ultimate strategic goals and act accordingly.

Building a Europe that is “whole, free, and at peace” is still an achievable goal. It will require a renewed emphasis on European security, discarding the illusions of the past twenty years, and a clear focus on Europe’s new security challenges.