Sukotto, please, if you can't discuss something without rubbing your partisan agenda in everybody's face, then
SHUT THE HECK UP. This is about Japan. Not about Iraq, or how much you hate Bush, or how you can't wait for Hillary to become president for a 3rd term. Check your baggage at the door, or go post on moveon.org.
Now, as for the relevant stuff you had to say:
If the US was not in that part of the world would N&S Korea fight?
At this point in history I do not believe they would.
Nor do I believe NKorea would try to attack Japan.
What would they have to gain?
Dictators are always paranoid, and with the US attacking a country (Iraq) which posed no threat to it or even to its neighbors (Iran, nor Kuwait feared Iraq at the time of invasion), nor even had any nukes or other such WMDs, is it any wonder NKorea would try to at least make it look like they were creating a deterant?
Why would NKorea want to attack Japan again?
First, the Korean War never ended. A ceasefire is not a treaty, and North Korea and South Korea are not defined as political entities by a formal peace treaty, hence, they do not recognize one-another.
As for Japan, the North Korean government provides asylum to members of the Japanese Communist League/Red Army Faction, who hijacked a Japanese plane back in 1970. The KNCA is regularly claiming that minor statements made in American, Japanese, and South Korean politics and news as "declarations of war" and is constantly rattling its saber. Half the reason the Japanese have been considering removing Article 9 from their constitution is because they are afraid of N. Korea.
As for creating a deterrant, the North Koreans have been pursuing nuclear capabilities for years. In 1991, the U.S. withdrew its nuclear arsenal from S. Korea, and despite attempts by Bill Clinton, against Republican opposition, to negotiate with N. Korea, they still tested an ICBM by flying it over Japan and claiming it was a "satellite launch" in August, 1998, scaring the crap out of Japan. But Taepodong-1 missiles are not built to launch satellites.
I don't know what Kim Jong Il thinks he has to gain. Personally, I think he wants to keep his cushy lifestyle, and thinks that if he scares the rest of the world enough, and brainwashes his own people enough, he can keep his position of privilege.