WASHINGTON (AP) -- Republican presidential nominee Donald Trump's suggestion that the United States might abandon its NATO treaty commitments has upended decades of American foreign policy dogma and doctrine in both parties. It has created a domestic furor and fueled angst not only across Europe but in Asia, where Trump's complaints about allies not paying their own way have also resonated.
Trump's mere musing that he would review allies' financial contributions — in this case those owed by Estonia, Latvia and Lithuania — before acting under NATO's Article 5 mutual defense clause if they were attacked by Russia could rock the foundations of the security architecture that has underpinned European stability since the end of World War II.
That possibility, and the global instability that would likely follow, is not something NATO leaders or their nervous citizens will countenance lightly, particularly since they responded, without question, under Article 5 when the United States was attacked on Sept. 11, 2001.
U.S. administrations have complained, often bitterly, that many NATO members are not footing their share of the alliance's bills. The U.S. accounts for more than 70 percent of all NATO defense spending. Only four other allies — Britain, Estonia, Greece and Poland — meet the minimum 2 percent of gross domestic product on defense that NATO requires. But Trump's floating the idea that that spending target would be a prerequisite for the U.S. to defend them is an abrupt break for the most powerful member of NATO, which styles itself as the most successful military alliance in world history.
Estonian President Toomas Hendrik Ilves noted pointedly in a tweet that Estonia "fought, with no caveats," on behalf of the U.S. in Afghanistan.
In 2002, the only time Article 5 has ever been invoked, NATO surveillance planes patrolled American skies and deployed a third of the troops in Afghanistan for a decade. More than 1,000 non-American troops died in Afghanistan.
"We are equally committed to all our NATO allies, regardless of who they may be. That's what makes them allies," Ilves tweeted.
His fellow Eastern European leaders sought to calm the furor.
"Regardless of who will be the president of America, we will trust in America," Lithuanian President Dalia Grybauskaite told reporters in Vilnius in remarks that were echoed by Czech Prime Minister Bohuslav Sobotka. "The United States always stood with nations which were under attack and it will continue doing so."
NATO chief Jens Stoltenberg said "solidarity among allies is a key value for NATO," a stand that "is good for European security and good for U.S. security," he said. "
"The United States has always stood by its European allies. Now the U.S. is stepping up its support once again, and increasing its presence," Stoltenberg said. The U.S. placed new troops recently in Poland.
Yet, analysts and citizens throughout Eastern Europe, where fears of Russian aggression run high since it annexed the Ukrainian region of Crimea, expressed deep concern, notably since just two weeks ago NATO-country leaders reaffirmed that they "stand together, and act together, to ensure the defense of our territory and populations, and of our common values."
In Warsaw, average Poles were alarmed.
"His words were irresponsible and they inspired fear in me. I'm worried about the world's future, about Poland's future," said 39-year-old schoolteacher Lidia Zagorowska.
"If I were a U.S. citizen I would never ever vote for Trump. Let that be my answer," said Katarzyna Woznicka, 54, walking her dog in downtown Warsaw.
Others dismissed it as just political rhetoric. But back in the U.S., the outcry from politicians, including some of Trump's fellow Republicans, was blistering.
Senate Republican leader Mitch McConnell, who backed Trump at the party's national convention only two days earlier, said he totally disagreed with the statement but was willing to "chalk it up to a rookie mistake."
McConnell called NATO "the most successful military alliance in the history of the world" in a Facebook interview with The New York Times.
A former presidential contender, Sen. Lindsey Graham, R-S.C., said Trump's remarks "make the world more dangerous and the United States less safe. ... I'm 100 percent certain how Russian President (Vladimir) Putin feels - he's a very happy man."
Some Republicans opposed to Trump have sought to cast him as pro-Putin, a position that would put Trump at odds with both Republican and Democratic foreign policy experts and would diverge from the current GOP platform. While Trump surrogates may have succeeded in preventing a reference to arming Ukraine from getting into this year's GOP platform, the manifesto itself is demonstrably not pro-Russia.
In fact, it accuses "current officials in the Kremlin" of eroding the "personal liberty and fundamental rights" of the Russian people."
"We will meet the return of Russian belligerence with the same resolve that led to the collapse of the Soviet Union," it says. "We will not accept any territorial change in Eastern Europe imposed by force, in Ukraine, Georgia or elsewhere, and will use all appropriate constitutional measures to bring to justice the practitioners of aggression and assassination."
Secretary of State John Kerry reaffirmed the United States' commitment to NATO.
"This administration, like every single administration, Republican and Democrat alike since 1949, remains fully committed to the NATO alliance and to our security commitments under Article 5, which is absolutely bedrock to our membership and to our partnership with NATO."