When President Barack Obama attended a NATO summit in Warsaw earlier this month, he had one core goal: to reassure jittery members of the 67-year alliance that the U.S. would defend them against Russian aggression.

“As treaty allies, we have a solemn, binding Article 5 duty to defend each other. And in this obligation, we will never waver,” Obama said.


Article 5 is the provision in the NATO treaty under which an attack on any one member is treated as an attack on the whole alliance, triggering an automatic collective response. And it is a provision that Donald Trump cast into unprecedented doubt in a Wednesday interview with The New York Times, in which he said he would defend the Baltic states against a Russian invasion only if he deems that those countries have “fulfilled their obligations to us.”

The comments sparked a furor among Republicans, just as Trump was hoping to unify the party. From Senate Majority Leader Mitch McConnell on down, senior GOP figures rushed to register their disagreement. One, Rep. Adam Kinzinger, told a POLITICO event that the comments made it harder for him to support Trump.

“It’s utterly disastrous" said Kinzinger. "And you have allies right now, I mean I have friends that, you know, serve in parliament in places like Estonia, that every day worry about the Russians deciding that this is the time to reannex and take them back,” said Kinzinger, a former Air Force pilot. “And comments like this are not only ill-informed, they’re dangerous.”

During Obama’s presidency, foreign policy has been the subject of rollicking partisan debate on issues ranging from Iran’s nuclear program to Syria’s civil war to America’s troop presence in Iraq. But Republicans and Democrats almost uniformly agree on the value of a strong and credible NATO alliance.

And until Trump's remarks Wednesday, no major figure in either party had so openly questioned the NATO principle of collective defense.

Indeed, some experts call Trump’s position virtually unprecedented in the Washington debate.

“I don't know anyone, anywhere on the political spectrum who would question whether we should uphold Article 5. I’ve just never head that before,” said Philip Gordon, Obama’s former top national security council aide for Europe. “Whether it’s Bernie Sanders or Ron Paul, no matter how noninterventionist they are, I’ve never heard it,” added Gordon, who is also an adviser to Hillary Clinton’s campaign.

"There's no precedent," agreed Thomas Wright, a Europe scholar at the Brookings Institution, who said talk of rolling up NATO has been confined to the margins of academia.

This month’s NATO summit in Warsaw was largely designed to send a message of strength and unity to a resurgent Russia. NATO’s Eastern European and Baltic members — who have dark memories of Soviet domination — are particularly alarmed over Vladimir Putin’s aggression in Ukraine and a recent surge in Russian military muscle-flexing.

For once, Obama’s rhetoric chimed with that of his toughest Republican GOP critics. Florida Sen. Marco Rubio had urged Obama to use the Warsaw summit to “reiterate to our closest allies that the United States continues to stand with them,” which is precisely what Obama did.

Obama's remarks in Poland amplified his message from September 2014, when he flew to the Estonian capital of Tallinn, about 150 miles from Russia's western border.

"I say to the people of Estonia and the people of the Baltics, today we are bound by our treaty alliance," Obama said in a historic concert hall.

To growing cheers, Obama reassured a nation annexed by the Soviet Union that it would not be conquered again: "We have a solemn duty to each other. Article 5 is crystal clear: An attack on one is an attack on all. So if, in such a moment, you ever ask again, 'Who will come to help?', you’ll know the answer: the NATO Alliance, including the Armed Forces of the United States of America."

Such reassurances are hugely welcome by NATO countries on Russia’s periphery, who fear they could be the next target for Putin. The Russian leader annexed Crimea from Ukraine in 2014 and is backing a pro-Russian separatist movement in eastern Ukraine. Putin also invaded and seized portions of the neighboring Republic of Georgia in 2008.

Now some former senior Obama officials worry that Trump has undermined America's message of support, including the symbolism of this month’s NATO summit.

“We’ve been making progress,” said Evelyn Farkas, who served as deputy assistant secretary of defense for Russia, Ukraine and Eurasia until last fall. "There’s generally a lack of confidence within Europe that was ameliorated to a healthy extent by the NATO summit. We sent a very strong signal and backed that up" with new U.S. military deployments to Poland and the Baltics and major NATO military exercises this summer.

“We went from reassurance to deterrence in Warsaw. This throws into question the role of the U.S. as a world leader,” Farkas added.

Soon after Trump's remarks were published, his campaign manager, Paul Manafort, said the Times had misquoted the GOP nominee. On Thursday, Manafort told reporters that Trump was not setting a new bar for the defense of NATO allies, saying, "what Mr. Trump has said consistently is that he thinks NATO needs to be modernized.”

Across the aisle, Republicans and Democrats have long grumbled about the failure of NATO's European members to contribute more to the alliance’s budget — though virtually none have suggested withholding defense of members to make them pay up.

The U.S. currently pays about 22 percent of NATO’s annual budget, about twice what France and the United Kingdom kick in. Only four of NATO’s 28 members currently meet a pledge to spend at least 2 percent of their gross domestic product on the alliance.

Obama has complained that those members amount to “free riders,” as he recently put it to The Atlantic, mooching off American largesse. Senior Republicans have echoed that point. Last month, Senate Foreign Relations Chairman Bob Corker called it “highly offensive” that Germany doesn't spend more on the alliance.

Germany is NATO's second-largest contributor, pitching in about 15 percent of the alliance's budget, or nearly $40 billion. That is still only 1.8 percent of German GDP, however.

It is not clear what Trump meant when he spoke of the Baltics’ “obligations.” The pledge to spend 2 percent of GDP is a nonbinding political commitment among NATO members, and few meet it. The NATO treaty contains 14 articles, including requirements that members not enter into treaties that might conflict with the NATO pact and that they “maintain and develop their individual and collective capacity to resist armed attack.”

Some officials have warned for years that the heartburn over NATO's budget could pose a larger threat to the alliance's support in Washington. In 2011, Defense Secretary Robert Gates warned of “the blunt reality” that “there will be dwindling appetite and patience in the U.S. Congress — and in the American body politic writ large — to expend increasingly precious funds on behalf of nations that are apparently unwilling to devote the necessary resources or make the necessary changes to be serious and capable partners in their own defense.”

But Gates said nothing to suggest a retreat from America’s commitment to NATO’s Article 5.

Some experts fear that Gates’ prediction may be bearing fruit, and that Trump is exposing another fault line between Washington elites and the public. Most Americans would struggle to name the three Baltic nations — Latvia, Lithuania and Estonia — much less stomach a war in their defense.

Others insist the public understands the value of NATO, especially in light of Putin’s recent provocations. Ivo Daalder, a former U.S. ambassador to NATO under Obama, cited a recent poll by the organization he now heads. The July survey by the Chicago Council on Global Affairs found strong public support for NATO within the U.S., with Americans in favor of maintaining or increasing support for the alliance by a 75-21 percent margin. Fifty-seven percent of Republicans called NATO “essential” to U.S. security.

Even Trump’s running mate, Indiana Gov. Mike Pence, has banged the drum for a tougher NATO. In remarks during an April 2014 visit to Berlin, Pence trashed Obama’s first-term “reset” policy with Russia as “appeasement,” and, citing “Putin’s aggression in Ukraine,” called for the U.S. to deploy “a robust missile defense system in all of Europe — including Poland and the Czech Republic — to protect the interests of our NATO allies and the United States in the region.”

After Trump’s Times interview raised a ruckus in foreign policy circles, many top Republicans trashed his equivocal words about defending the Baltics. But one defender emerged in former Republican House Speaker Newt Gingrich, who was a finalist to be Trump’s running mate.

"[NATO] countries ought to worry about our commitment," Gingrich told “CBS This Morning,” citing their failure to “pay their fair share."

Gingrich added that Estonia “is in the suburbs of St. Petersburg,” adding: “I’m not sure I would risk a nuclear war over the suburbs of St. Petersburg.”

That was a different tune than the one Gingrich sounded after Putin’s annexation of Crimea in 2014. Gingrich criticized Obama for not more forcefully deterring Russia, thereby inviting Putin’s aggression.

“I worry about this both in terms of Crimea and what happens to Ukraine but also in terms of what lessons does he learn about dealing with Estonia, Latvia and Lithuania, who are members of NATO and are on the northern Russian flank?” Gingrich asked in a March 3, 2014, appearance on CNN.

“It's very important that Putin understands there are consequences to this kind of aggressiveness,” he said. “But I do think that the United States and Europe did a lot to set up the crisis.”

That is precisely what experts and policymakers in both parties are now saying about Trump’s incendiary comments.