Summary: Why North Korea could become one of President Obama’s most vexing foreign-policy challenges: For the moment, the Obama White House has bigger priorities than North Korea. Still, the new U.S. president would do well to keep in mind that Pyongyang is continuing to tweak its nuclear-weapons program. It already has an arsenal of ballistic missiles capable of hitting all of Japan and potentially parts of the United States. For all its paranoia, North Korea insists it’s still under the threat of “American and Japanese imperialists,” and says that it has every right to possess a “nuclear deterrent” to defend itself. Appeasing them with money and oil won’t be enough.