While it's not unusual for North Korea to threaten it's neighbours, the talk issued from Pyongyang on Monday was harsh even for their standards. Not only did they state that any effort to prevent North Korea from launching a satellite into space (widely believed to be a cover for a nuclear test), but they threatened to shoot down South Korean passenger aircraft that approaches the demilitarized zone.
Yesterday, according to this article in the Globe and Mail , North Korea is vowing to take "every necessary measure" to protect itself against what it perceives as a U.S threat. Every year the United States and South Korea participate in military exercises that they claim are simply defensive in nature, but the North states are planning for an invasion of their Communist state.
What is really dangerous during this is that Pyongyang cut off all communications with Seoul. Every once in a while there are accidental firings across the border, usually not aimed at anyone in particular, but each one has the potential to escalate even in normal times. For it's part, South Korea has a standing policy to return every shot received with an equal response.
During the war games, even an accidental shot fired across the worlds most heavily armed border could spell absolute disaster. That is if the North doesn't decide to take the initiative and launch an attack on purpose.
Having lived in South Korea for several years, I realize that most people don't even expect that the possibility of conflict could happen, but I think that the perspective of the people in South Korea is very far from the perspective of the North Korean government.
South Korea is a prosperous, developed and peaceful country that has built itself up out of the ashes of Japanese occupation and a brutal internal war to become one of the world's largest economies in just a matter of decades. The North hasn't left the bunker mentality that they had since the war ended. They have not enjoyed the economic prosperity of the South; on the contrary. As the South grew, the North languished, especially after the fall of the Soviet Union. Their mentality must be affected by the mass starvation and utter reliance upon foreign oil given in exchange for talks.
With South Korea holding back it's oil gifts until Pyongyang disables its nuclear program, the North might be thinking that this is its last chance to fight. A country that can't feed it's people, can't sustain it's rustbelt industries, and can't get access to oil cannot be much of a threat for long. I hope that they don't do anything stupid, but they might be seeing this as their last, best chance.
From a number of South Korean and U.S military people with whom I've spoken, I gather that they very much expect that the South's lines would be overrun very quickly. That is until Northern forces were to reach the perimeter of Seoul when the North would begin to weaken. They could get off a good deal of explosives, but South Korean counter strikes could eliminate the North's ability to launch missiles and aircraft very quickly. Though the South has a much smaller military force, it's military is well equipped, modern and has fuel. The North's force simply could not endure a sustained conflict.
Perhaps they (North Korea) are thinking that the U.S is too busy in other places to respond, or that Barack Obama is a pacifist who wouldn't want to sacrifice lives in order to defend South Korea. On the contrary. Defence of South Korea is a top priority for the U.S and any administration which failed to honour it's commitment would risk alienating many U.S allies and much of the U.S public. It would be along the lines of the U.S failing to defend a NATO member.