Pyongyang's latest nuclear test is another reminder of the seemingly intractable "problem" of North Korea. The country's pursuit of nuclear weapons has apparently been unstoppable. First quietly in the 1980s but lately rather overtly, North Korea has proceeded with its weapons program despite sanctions, isolation, military threats, and attempts at engagement and reconciliation. At a time when the United States is moving toward normalizing relations with Cuba and extolling "historic progress through diplomacy" with Iran, U.S. relations with North Korea are increasingly anachronistic. But Pyongyang's conventional military capability, its often-convoluted relations with its neighbors and the United States, and the ambiguous examples of other states' paths to developing or abandoning nuclear weapons have made "solving" the North Korean problem a complex challenge indeed.