Thank you, Neal. Other big news today. President Obama hurled a verbal rocket at Vladimir Putin. He said we're not in altogether cold war, but they should not think they can go against a nato nation.... See More
Thank you, Neal. Other big news today. President Obama hurled a verbal rocket at Vladimir Putin. He said we're not in altogether cold war, but they should not think they can go against a nato nation. Here's Jonathan Karl. Reporter: In a solemn reminder of the costs of european wars, president Obama laid a wreath in honor of Americans who died to liberate Belgium during world war I. This hallowed ground reminds us that we must never, ever take our progress for granted. Reporter: Later, the president accused Russia of threatening the order that has kept the peace in Europe for 70 years. Russia's leadership is challenging truths that only a few weeks ago seemed self-evident. That in the 21st century, the borders of Europe cannot be re-drawn with force. That international law matters. Reporter: While he said the Ukraine crisis cannot be solved militarily, the president also drew a line, saying nato countries, including those nervously on Russia's border, will be defended at any cost. In that promise, we will never waver. Nato nations never stand alone. Reporter: Today, a leading Russian politician responded to president Obama's statement yesterday that Russia is just a regional power, saying, quote, "Russia was, is, and always will be a global power. Meanwhile, the Russian troops tonight to mass along Ukraine's border.
This transcript has been automatically generated and may not be 100% accurate.