Team Obama’s debut on the world stage at last weekend’s security conference in Munich was highly anticipated. With his pledge for a "new era of cooperation," Vice President Joe Biden struck the right note for a European audience still haunted by the Bush administration’s "with us or against us" approach. But once the memory of Bush fades, Europeans will realize the price of Barack Obama’s multilateralism. Like the U.S. president, they’ll be forced to define what kind of multilateralism they want and what they’re willing to sacrifice for it. More than any other issue, Afghanistan will produce this moment of truth sooner than might be expected, while determining NATO’s relations with Iran to a greater extent than expected.