After years of provocations, talks, promises and broken vows — a pattern that Pyongyang has mastered — the atmosphere on the Korean Peninsula remains highly charged and little changed.

But the same question remains: What can be done about North Korea?

With its fourth nuclear test and rocket launches that critics say mask a drive to create a long-range missile capable of striking the United States, North Korea's recent repeated acts of belligerence are a familiar refrain.