Why are the troubles in Ukraine unsettling to Americans?

The tension over Ukraine presents inevitable comparisons to the Cold War.

Russia has annexed Crimea and pro-Russia sympathizers in eastern Ukraine are angling for the same fate.

Ukraine's military is trying to quell the unrest.

NATO forces are swirling around the region trying to reassure their newest members Lativia, Lithuania and Estonia and send a message to Moscow. And the United States is trying to do something meaningful without coming to blows with Moscow.

Remember, Russia is still the most heavily armed nuclear power in the world after the United States.

But somehow what stands out from a distance is the Russian insistence that they retain their sphere of influence.

Think Warsaw Pact light. No amount of scolding from President Obama has seemed to move Vladimir Putin from his position that Crimea belongs to Russia and Ukraine must, at the very least, do nothing to antagonize Moscow.

One of the most stunning aspects of the tension over Ukraine is Putin's utter and complete defiance.

The Russian president is open about his intention to restore the glory of Russia after the period of humiliation following the Soviet collapse, what Putin has called "the greatest geopolitical catastrophe of the 20th century." 

Putin's angry speech in March was a 45-minute denunciation of the United States and its allies in the years after the Soviet collapse in 1991.

"They cheated us again and again, made decisions behind our back, presenting us with completed facts," said Putin. "That's the way it was with the expansion of NATO in the East, with the deployment of military infrastructure at our border. They always told us the same thing: 'well, this doesn't involve you.'"

That sense of being ignored and treated like a small and second-rate country is something we Americans may have missed.

Perhaps we thought that life after the Soviet Union would be one long roll-out of Western-style democracies across eastern Europe, with Russia re-emerging (eventually) as a regional economic power that would embrace a diminished political role.

Not so. The frustration and anger that Putin expresses is felt by many Russians, not just former apparatchiks. And they share Putin's desire to make Russia strong again, at the very least within its own region.