In announcing new sanctions on Russia last week, U.S. President Barack Obama was at pains to insist that the standoff over Ukraine doesn't mark the beginning of a new Cold War.

No doubt he's right — but commentary on the Ukraine crisis has continued to embrace the Cold War analogy anyway. International observers have done so, too. So have some Russian commentators: "Russians Will Suffer in Putin's New Cold War," warns the opposition Moscow Times.

Apparently lots of people in the U.S. have similar worries. As I've traveled this month to promote "Back Channel," my novel about the Cuban missile crisis, audience members have peppered me with questions about what they see as the dawning of a new Cold War.