What was the Korean War about?

[CynicalIdealist]

Get used to my dumb questions. >_>

I've heard the right-wing mainstream accounts of "North invasion," I've heard other accounts suggesting that both countries wanted to reunify (the North jumping the gun), and I've heard accounts that the South attacked first and provoked an invasion by the North. What were the motivations of both governments, and the main reasons why the war began? Would it have been waged without a U.S. invasion?

[khad]

Both sides had been preparing to fight for years, but it is true that in 1949 Rhee in the South launched a campaign of probing attacks into northern territory.

[Princess Luna]

When the Japanese pulled out after WW2 the north was left in the hands of the soviets and the south in the hands of the Americans and when those countrys pulled out they left behind governments friendly to there respective ideology , as tensions build up with each side demonizing the other it reached a head in 1950 when North Korea launched a invasion of the south. The invasion was very successful , and in a short amount of time they overwhelmed South Korean troops and took most of the south. The tide turned when U.N. forces (the irony is the U.N. declaration of war against NK could have been vetoed by the Soviet Union had they not left the U.N. in protest of the RoC getting china's seat) led by the U.S. launched a counter attack driving the north back across the border. The U.N. led forces managed to take Pyongyang and in a massive display of stupidity vastly reduced all incoming supplies assuming they had won the war and not only ignored all warnings from the Chinese to leave the north but also pushed towards the border that seperated China and NK. Even when Prisoners claiming to belong to the Chinese army were captured and farmers began to report seeing 1000's of Chinese troops moving south the the U.S. high command ignored it. So when the Chinese did strike the U.N. and south Korean forces got their ass kicked and were driven back across the border were for the next 3 years a bloody stalemate would ensue with both sides suffering horrible losses until finally a truce was signed.