North Korean suicidal intentions not withstanding, they are expert at "stirring the pot" to gain strategic advantage and are now playing the nuclear card for all its worth. Instead of permitting direct talks to develop through the "gang of six" the DPRK has chosen direct confrontation to keep itself on the world stage. An invasion of South Korea by the north would be a logistical nightmare that grinds to a halt nearly as soon as it crosses the DMZ. There exists nearly no serious threat to other ASEAN countries other than discarded test missile stages from time to time.
Chinese influence peddling by DPRK as proxy is a possibility, however unlikely. A cold war unilaterally initiated by China without regard for it's recent economic doldrums is more ominous than any bleating by North Korean war sheep. However at the moment China is rather preoccupied by concerns over Bird Flu ramifications and ASEAN countries should be wary of how this affects the recent 40% rise of Chinese tourism overseas.
CNN sensationalism notwithstanding, I wouldn't lose any sleep over any any threats to Japan, the Republic of the Philippines or ASEAN countries outside of South Korea at this time or in the immediate future especially from North Korea. The Balikatan exercises in the RP of only 12 days duration (ideal to utilize Reserve units for their "summer camps") have been going on for many years and have become more relevant recently in light of what the RP Foreign Secretary himself remarked on the latest training evolution: "For our region excessive and exaggerated maritime and territorial claims have not only created uncertainty but have undermined the rule of law,' Del Rosario said in a speech at the nation's military headquarters in Manila. "Regional peace and stability have been placed at serious risk.' Del Rosario later said he was referring specifically to China." ( http://ph.news.yahoo...-061158850.html )
As Reuters has also pointed out in it's reporting, the RP lost it's tactical air component a decade ago after retirement of it's F-5 aircraft and has never replaced them. They have purchased older airframes only suitable for transport and logistics support for disaster relief operations, so that part of the current exercise is highly useful where only the U.S. can support such large scale operations to make this equipment operational and train some troops in the process.
Quite obviously the RP benefits from it's 61 year Mutual Defense Treaty as do other ASEAN countries in the region. The recent posturing of North Korea only plays into U.S. strategic designs to move military assets back into the area to strengthen these ties. Remember that a state of war has always existed on the Korean peninsula. South Korea is capable of defeating the DPRK and the U.S. has the actual capability to rapidly double these defense forces in theater in a matter of hours in most cases. However the urban warfare that could in likelihood erupt in Seoul is a major concern and would cause widespread suffering in South Korea. Therefore the real threat is to the region's economy and subsequently the world economy. The developed countries struggling to regain economic prosperity after continuing deflation in Japan's case and the failure of austerity programs in Europe have more to lose than the developing world which has been expanding albeit in a more restrained fashion thus almost flying under the radar of most not directly involved in the world of finance itself or even aware of actual foreign affairs.