A nonendorsement speech dominated the news from the third night of the Republican National Convention, obscuring a much more important development in Donald Trump's campaign for the White House.

Asked by the New York Times on Wednesday whether the U.S. would immediately provide military aid to a Baltic nation if Russia were to invade, Trump answered: "Have they fulfilled their obligation to us? If they fulfill their obligation to us, the answer is yes." Asked then "and if not?" Trump responded: "Well, I'm not saying if or not. I'm saying, right now there are many countries that have not fulfilled their obligation to us."

NATO, the world's essential military alliance, is predicated on each of its 28 members upholding treaty-bound obligations to treat an attack on one as an attack on all. The trigger mechanism for this vow, Article 5, has been invoked only once — by the United States after 9/11, when NATO forces fought, and died, along with U.S. troops in the war in Afghanistan.

Responding to Trump, NATO Secretary General Jens Stoltenberg underscored the importance of the alliance. "Solidarity among allies is a key value for NATO," Stoltenberg said in a statement. "We defend one another. We have seen this in Afghanistan, where tens of thousands of European, Canadian and partner nation troops have stood shoulder-to-shoulder with U.S. soldiers. Two world wars have shown that peace in Europe is also important for the security of the United States."

The Cold War, too, showed the need for NATO. And although the Soviet Union lost, a revanchist Russia has annexed Crimea, destabilized Ukraine, and menaced multiple European and especially Baltic nations with military provocations. So Estonia, Latvia and Lithuania have reason to fear Vladimir Putin's Russia, and now reason to be concerned about the uncertainty a Trump presidency would bring.

"We are equally committed to all our NATO allies, regardless of who they may be. That's what makes them allies," Estonian President Toomas Hendrik Ilves tweeted in response to Trump's comments.

That sentiment has been shared by U.S. presidents from Harry Truman to Barack Obama, including six Republicans who were stalwart supporters of NATO. Current GOP lawmakers should be as alarmed as their Democratic colleagues over the signal Trump sends potential adversaries, who may be tempted to test NATO resolve. A resulting militarily miscalculation could spark a conflict that would cost lives and further destabilize geopolitics. To their credit some Republicans, including Sens. Lindsey Graham and Ben Sasse, have spoken out.

Unequal contributions from NATO nations are in fact an issue. But common defense should never be predicated on this ongoing issue. After all, the best NATO defense is the certainty that any adversary would face the unreluctant wrath of 28 nations.

Trump's questioning of NATO and other essential U.S. alliances isn't conservative. It's recklessly wrong and should be rejected by Republicans and Democrats alike in a bid to reassure alienated allies that the U.S. stands by its treaty obligations.