But why is the U.S. worried about the so-called Democratic People’s Republic of Korea? It’s a distant and poor country surrounded by far more powerful states; it is an economic irrelevancy and a diplomatic nonentity. Most important, it has no effective means to attack America. North Korea should be a problem for other nations -- for China and Russia, the most important regional powers, and for Japan and South Korea, America’s closest regional friends. All have more at stake in the North than we do. Indeed, the only reason Washington is entangled in the Korean peninsula is inertia: The U.S. has defended South Korea for 50 years.