The United States is a bit like a 375-pound, middle-aged man with a heart condition walking down a city street at night eating a Big Mac. He's sweating profusely because he's afraid he might get mugged. But the thing that's going to kill him is the burger.
Since the end of the Cold War, America has been on a relentless search for enemies. I don't mean a search in the sense of ferreting them out and defeating them. I mean that America seems to have a visceral need for them.
Many in the United States have a rampant, untreated case of enemy dependency. Politicians love enemies because bashing them helps stir up public sentiment and distract attention from problems at home. The defense industry loves enemies because enemies help them make money. Pundits and their publications love enemies because enemies sell papers and lead eyeballs to cable-news food fights.
The Greeks, who once seemed to know a lot more about life than they do about fiscal management today, noted that for any drama to succeed it requires agon -- conflict. The same seems to hold true for politics and foreign policy. It's easier to run against a threat than it is to articulate a vision of where we should be headed and how to get there. Absent clear dangers, it's hard to persuade people to fund giant defense and intelligence establishments or to mobilize international coalitions. (Just add up how many international coalitions are primarily against things -- enemies, hunger, disease, climate change -- rather than for things.)
For the World War II generation, there were the Germans and the Japanese, vilified so much that even today they are the enemies against whom all others are measured. Then there were the Soviets, who were both dependably evil and happened to be a genuine threat. After the communist collapse, America tried to replace them but came up at first only with tin-pot bad guys like Manuel Noriega, Slobodan Milosevic, and "Baby Doc" Duvalier.
Then came the 9/11 attacks, and politicians simply crossed out the word "Soviet" in their stump speeches, replaced it with "terrorist" (despite the huge disparity in the nature and scope of the threats), and started scaremongering and spending like the good old days.
Now, as the United States winds down the wars that came of that, there seems to be a search for new bogeymen. In March, Republican presidential candidate Mitt Romney called Russia America's "No. 1 geopolitical foe," following up on his December complaint that Vladimir Putin is "a real threat to the stability and peace of the world." But in February he was warning against the risks posed by China's "prosperous tyranny." In March, it was nuclear North Korea, one of the "world's worst actors." Back in 2009, Romney wrote an op-ed calling Iran "the greatest immediate threat to the world since the fall of the Soviet Union, and before that, Nazi Germany," while in 2007 he called jihad "this century's nightmare."