The West faces a dilemma now that Russian President Vladimir Putin has demonstrated his willingness to win at any cost in Ukraine: Does it, too, go all in, or does it admit Putin's de-facto sovereignty over Russia's post-Soviet neighbors? Both options are unpalatable, and the right answer depends on whether Putin plans to go beyond subjugating Ukraine.

"Arm Ukraine or surrender," is the way commentator Ben Judah formulated the Western world's dilemma in the New York Times. "American and British special forces should be dispatched to plant the flag and protect the airports of Kiev and Odessa," he wrote, warning that the alternative is "a surrender, too, for NATO, for Europe and liberal democracy, and for American global leadership."

Making that argument requires certainty that, after clawing back Ukraine, Putin will want to do the same to the Baltic states, and perhaps even to the former Soviet Union's Warsaw Pact satellites. Judah thinks Ukraine is not his final stop. U.K. Prime Minister David Cameron reportedly warned his European colleagues against "repeating the errors of 1938 in Munich," referring to a pact the U.K. and France made with Hitler, allowing him to carve up Czechoslovakia.