So how would North Korea strike South Korea? We think that China might take care of the problem and say America will if China won't. But North Korea gets a vote, too.
Rather than comment on that article, let me spout off on my views. But do read the article.
My view is that North Korea has a few basic options.
North Korea has a lot of artillery and chemical weapons which are their major asset. I'm still assuming they don't have functional nuclear weapons as opposed to devices babied by armies of technicians and scientists. They have lots of troops with old equipment, poor training, and nutrition deficiencies that make them small as people. They have no large-scale combat experience since 1953.
The South Koreans have good troops that fought well in the Korean War and in the Vietnam War, and their equipment is modern they certainly have adequate training.
The balance favors South Korea with North Korea having only the advantage of initiating war before South Korea is ready or America and Japan can commit forces to the fight.
As to North Korean options.
One, North Korea could try to limit the risk of a ground war along the DMZ by initiating fighting along the sea border to the west. Send in subs, naval infantry, commandos, and surface ships to sink and kill as many troops and civilians as possible. Meanwhile the North Koreans dare South Korea to expand the war and risk the destruction of Seoul by artillery barrage.
Two, North Korea could unleash commandos in the south to sow disorder while their army makes a limited grab for territory north of Seoul and digs in south of the DMZ to hold the terrain and dare the South Koreans to kick them out and risk the destruction of Seoul that is now within reach of more of North Korea's artillery.
Three, North Korea could go for broke. They'd use option 1 plus the commando portion of option 2, and they'd add a massive offensive on the west side of the DMZ aimed for Seoul that, given the poor quality of the troops and equipment flung south would rely on an even more massive chemical weapons barrage to break the South Korean army and allow the North Koreans to conduct what is essentially a road march to Seoul and perhaps points south.
If the South Korean army breaks under the chemical barrage, it could be game over for Seoul unless the North Korean conscripts break ranks in the advance to plunder South Koran grocery stores and malls--and I'm partially serious, here. Armies have gotten confused about their priorities in history.
I suspect the South Koreans would reform their lines further south and hold. But with Seoul enemy occupied the war gets much more awful.
And we might have to nuke some North Korean bases as a retaliation for massed chemical weapons use, if we want to maintain deterrence. Without chemical weapons, in the past we relied on the threat of nukes to deter chemical use against our troops and our allies. But precision weapons mean we might unleash them as a substitute for nukes because precision means we can destroy targets that once needed nukes to take out.
Odds are the North Koreans suffer a major defeat trying to invade South Korea and that South Korean forces counter-attack to occupy an arc of territory north of the DMZ to push North Korean artillery out of range of Seoul.
And then the air-ground campaign by America, South Korea, and Japan against North Korea kicks into high gear to hunt leadership and WMD targets.
UPDATE: And yes, I am aware that discussion of Seoul being within range of North Korean artillery (tip to Instapundit) mostly means northern suburbs for the usual artillery and that hitting the heart of Seoul requires missiles, planes, and a limited number of larger caliber pieces.
Still, the damage will be heavy and given how a single errant round by America leads to massive complaints, I assume the damage to Seoul will be blamed on America to an even greater degree.
I also assume that predictions that America and South Korea can knock out North Korean artillery quickly underestimate North Korea's ingenuity. So I think the fewer assets that hit the heart of Seoul will fire far longer than optimistic assumptions.