What is there to gain for North Korea?

North Korea canceled the armistice agreement that brought a cease-fire to the Korean War, and threatened to destroy South Korea or turn Seoul into a sea of fire. North Korea vowed to cancel any agreements made between the two Koreas starting today, March 11. This date coincides with the date of the annual Key Resolve exercise. North Korea had condemned the annual joint maneuvers as a provocative invasion rehearsal. North Korea is using the exercise to create tensions in the Korean peninsula in order to gain leverage in other matters. However, the tides have changed and North Korea will no longer be able to get away with their provocative actions. This time it's very different. China no longer can support North Korea's insanity. And the US will not give in to North Korea's requests.
(http://www.munhwa.com/news/view.html?no=2013030801070323169002)