Maybe Europeans are not from Venus after all. In a rare display of unity and resolve, they are pouring advanced weapons into Ukraine, expanding NATO, kicking their addiction to Russian gas and tightening the economic squeeze on Moscow. With the reprehensible exception of Viktor Orban’s Hungary, our European allies seem determined to thwart Russian President Vladimir Putin’s brutish attempt to dismember Ukraine if not erase it from the map altogether. To the surprise of many Americans, the creaky old transatlantic alliance is beginning to look like a strategic asset again. Sweden and Finland, strictly neutral during the Cold War, are...