BRUSSELS, Belgium — He may regard it as Russia's arch-adversary, but Vladimir Putin has unwittingly given NATO a new lease on life.
Until the Russian leader marched into Crimea, the Atlantic alliance was searching for a new role.
Its long, costly war in Afghanistan is set to grind to a halt later this year after generating levels of public unhappiness that have cast doubt on the group’s post-Cold War ambitions to solve far-flung crises.
Underfunded, unloved and shaken by a decade of trans-Atlantic squabbles from Iraq to Edward Snowden, NATO was facing existential questions.
Now Putin has reminded Europeans and Americans what the alliance was originally created for.
"NATO’s greatest responsibility is to protect and defend our territory and our people,” the alliance's Secretary General Anders Fogh Rasmussen told reporters Tuesday. “And make no mistake, this is what we will do."
"Today, we reaffirm our commitment to collective defense," he said on the sidelines of a NATO foreign ministers' meeting. "We will deter and defend against any threat. We remain vigilant, ready and able to defend our allies."
During the meeting, the alliance pledged to strengthen the defenses of its eastern members such as Poland, Romania and the Baltic states, suspended all military and civilian cooperation with Russia, and stepped up support "to strengthen Ukraine’s ability to provide for its own security."
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Beyond the bold statements, however, the allies remain divided about how best to deter Putin from escalating tensions further.
The United States has sent small military detachments to eastern NATO members and joined other allies in dispatching fighter jets to Poland and the Baltic states. The Poles and Balts, who feel directly threatened, are seeking a tougher stance. Others — including the Germans, Dutch and Italians — are wary of any steps that could provoke the Kremlin. They’re searching for a diplomatic de-escalation.
Diplomats said the Germans and Dutch were privately fuming at an appeal from Poland for up to 10,000 heavily armed NATO troops to be stationed on its territory.
Poland joined NATO in 1999 along with Hungary and the Czech Republic. Seven other former Soviet bloc countries entered in 2004. To calm Russian nerves over the eastern expansion, NATO agreed not to position significant military assets in its new eastern members.
For some allies, Putin's occupation of Crimea and massing of around 40,000 heavily armed troops close to Ukraine's borders now invalidates such agreements from rosier times.
“We want Poland to be defended by the military, not only by words written in a treaty," Prime Minister Donald Tusk said Tuesday in Warsaw.
The Poles see frightening historical parallels. In 1939, France and Britain were bound by treaty to protect Poland, but were unprepared and unable to help when Nazi Germany overran the country at the start of World War II.
NATO headquarters is at pains to point out that the alliance has what it takes to defend all its members under Article 5, the clause in its 1949 founding treaty stating that an attack on one ally will be considered an attack on all.
"I can assure you that NATO always has all the plans in place in order to protect and defend the allies," NATO spokeswoman Oana Lungescu said in an interview. "The Article 5 collective defense provision is at the heart of NATO. All for one, one for all — that remains the core of the alliance and no one should be in any doubt that it will be upheld now and in the future."
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A US F-15 pilot scrambles during a NATO air force exercise in Lithuania on Tuesday. (AFP/Getty Images)
Nevertheless, Poland and other eastern countries have long complained that NATO has been neglecting that core task. They say it’s focused too much on missions in Afghanistan, Libya and fighting piracy off Somalia’s coast instead of updating planning and preparations to address a Russian threat in Europe.
But during recent NATO summits, the easterners were warned against fear-mongering when they suggested that the Russian bear may not always be the cooperative "partner for peace" it was supposed to become under a 1994 military cooperation agreement.
This week, US Secretary of State John Kerry said allied military planners were working urgently to provide "visible reassurance" that "Article 5 of NATO’s treaty means what it says on land, air, and sea."
That doesn’t mean NATO will go to war to defend Ukraine. France and Germany blocked its bid to join the alliance in 2008 because of fear of annoying Putin. They also stalled Georgia's attempt to join four months before Putin invaded that former Soviet neighbor anyway.
Western leaders say a Russian invasion of Ukraine would be met with economic sanctions instead.
Still, there is real fear in the alliance’s headquarters that a Russia-Ukraine war could spill over into a wider conflict. Fogh Rasmussen has called the crisis over Ukraine the most dangerous in a generation.
There are plenty of nightmare scenarios.
Western pressure to intervene would mount if a Russian invasion were to result in heavy civilian casualties, atrocities or a massive influx of Ukrainian refuges into the European Union. Russia could be tempted to lash out in the Baltic States in response to biting economic sanctions, or if its forces were met with significant resistance in Ukraine.
Although the allies are divided over whether such outcomes can be best avoided through deterrence or appeasement, the crisis is forcing them to face up to the need to refocus on territorial defense as NATO's 13-year mission in Afghanistan draws to a close this year.
Like the alliance's other post-Cold War operations, Afghanistan has produced mixed results.
Allied troops may have kept the Taliban at bay, trained effective Afghan armed forces and helped created an environment where this weekend's elections can take place. But there’s no doubt NATO's biggest-ever military operation has fallen short of initial hopes of helping build a peaceful, stable democracy.
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The battlegrounds of Yugolsavia, Kosovo and Bosnia — where NATO also intervened — are peaceful, although persistent divisions among their communities have kept them from joining Europe's mainstream.
Libya is a mess three years after the alliance’s airpower helped overthrow dictator Muammar Gaddafi.
But Ukraine will be an even bigger trial.
Even if conflict is avoided, intensified US calls for European allies to step up their defense spending will strain unity. Only Estonia, Greece and Britain currently meet the target of spending 2 percent of their economic output on defense.
However, the greatest challenge will be finding the political will to back up the declarations of solidarity, should Putin decide to put them further to the test.
Pursuing his personal vision: Putin at joint military exercises of Russian and Belarus troops in late 2013. (AFP/Getty Images)