In a speech largely dedicated to reassurance of newer allies and representing perhaps the most powerful expression of support from the US over the last 23 years of restored diplomatic relations, Obama made clear where the US stood on Baltic as well as Ukrainian independence.

"Just as we never accepted the occupation and illegal annexation of the Baltic nations, we will not accept Russia’s occupation and illegal annexation of Crimea or any part of Ukraine," he said. Among much else, he denied that NATO had second-class members. "The defense of Tallinn and Riga and Vilnius is just as important as the defense of Berlin and Paris and London."

Obama extolled Estonia's perseverance and achievements in establishing rule of law and digital progress - "one of the most wired countries on earth."

And he criticized Russia for, he said, losing its way.

Russia's actions - "dark tactics," said Obama - harked back to scenes of fleeing families and instability recognizable from the world wars.

"We have no interest in weakening Russia," Obama also said. "We do not seek out confrontation with Russia."

Obama said that the US had always supported the development of the rule of law in the country.

"That path remains available to Russia," said the President, "but it's a path that starts with Russia changing course and leaving Ukraine so Ukrainians can make their own decisions."

He also reserved a section of his address for Ukraine and the necessity of civil reforms, before calling for NATO to sned an unmistakable message to Ukraine as well - a country NATO has been partnered for more than 20 years. "Ukraine needs more than words," said Obama.

He counseled a rejection of cynicism and despair. The reason that he and his audience were in a democratic Estonia today in the first place, said Obama, was that "the Estonian people never gave up" during the countless slings and arrows of history.

The biggest round of applause from a crowd that seemed restrained about clapping in the beginning came when Obama quoted poet Marie Under. He answered her question - who will come to help? - with a resounding recaptulation of the essence of NATO's Article Five.

"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, 'right here, [at] present, now! We’ll be here for Estonia. We will be here for Latvia. We will be here for Lithuania. You lost your independence once before. With NATO, you will never lose it again."