From the outset of his presidential campaign, President Obama made clear he would pursue a different form of diplomatic strategy with countries that had traditionally been regarded as foes of Washington: He was willing to negotiate with them "without preconditions." And coming after the "axis of evil" years of the George W. Bush administration, that gave hope in some circles that a breakthrough could finally be on the cards between Pyongyang and Washington under Obama's watch.

But all was not to be: within months of his inauguration, North Korea launched a Taepodong-2 long-range rocket and less than two months later – following sharp criticism from the UN Security Council – conducted its second ever nuclear test. And so the scene was set for the next several years of policy with Pyongyang, worsened further by the Leap Year deal of 2012 falling apart just weeks after its agreement.