(Based on a true story, the same way that Operation Repo is.)
I got this question from a friend, thought I'd share with ya'll:
http://www.bbc.co.uk/history/worldwars/coldwar/korea_hickey_01.shtml
TL;DR: They didn't - the UN did. A multi-national force composed of US, UK, Australian, New Zealand, Dutch and several other countries, was asked by the UN to go to the assistance of South Korea as it was being over-run by North Korean troops.The military effort was commanded by the American Genreal McArthur.True the US did most of the fighting, but UK and commonwealth troops fought many battles and assisted the UN operation with as much bravery as the US troops.
That, or they were training for the Vietnam War. Who knows.
But honestly, as you say, my best guess: US had some serious penis-size-related issues when politics didn't work. So, they came and shoved their dicks up them Korean mothafuckers arses...
So why would the US display such a tremendous force in a country so far away (and this is where it gets interesting, and speculations occur): To show other countries, could be for example Vietnam (hint hint, nudge nudge, know what I mean?), that the US had great military power and was capable of overcoming any obstacle on their way in religiously spreading freedom to the entire world. Remember, as the Kwar was initiated, at the same time, the US was sending military advisors to assist the french armies in Naaaam in order to help them there, before the US themselves went there in 1959 when they had had enough of the yellow-skinned tint-eyed demons slaughter and mayhem bringing bannermen. Remember, this is all post WWII when the world was trying to settle down, or some were, like Europe and the US. Europe being highly influenced by the world war with a stagnating economy, relied on US troops to do the work. Many men died in WWII, european countries had no spare warriors to send, but the US, showing up late for the 'STOP - HAMMER-HITLER-TIME'-party, didn't lose as many men or suffer the same great continous losses as many european countries.
Also, US army consisted of seasoned veterans who wanted to go to war again, and kids (read: young adults, green soldiers) who would love to go to war again, because, US have throughout history had a war for every generation to participate in.
There are MANY MANY options for why the US should MOST DEFINITELY go to war. These are all possible options. I don't know which is right, the official reason will of course be: "We care about the poor innocent people whose houses are burned to the ground, the fatherless children and the rape of women... HURR DURR." But honestly, my best guess: US had some serious penis-size-related issues when politics didn't work. So, they came and shoved their dicks up them Korean mothafuckers arses...