Because that is where the enemies were.
North Korea attacked South Korea.
Probably how they did a surprise attack on South Korea.
North Korea attacked south Korea around 16 times.
because north Korea attacked them
An unprovoked attack by North Korea on South Korea in June 1950
Korea was a politcical war. The USA soundly defeated North Korea but was suprised by the Chinese in their all out attack. The USA would not do an all out attack against the Chinese for fear of starting a nuclear war with them and the USSR. In the end politics decided the tactics and ultimate stalemate. Had the USA kept General McArthur in command and fought to win they would have. The USA had more and better field commanders, aircraft, naval vessels and tanks but they lacked the will to use them.
To "Liberate" South Korea is the main reason for the North to attack. The North, which became communist after the Korean peninsula was freed from Japanese rule, wanted South Korea to become communist as well.
The US is not permitted to patrol North Korea, nor do they. The US military does however have military bases in south Korea as part of a treaty to protect them against a possible attack by North Korea.
1) The US and Russia are for the most part no longer "enemies". 2) North Korea is very likely to use any possible nuclear technology against South Korea, which is a US ally; I don't think Russia wants to attack South Korea. 3) As I said earlier, Russia is not likely to attack the US, North Korea is.
North Korea with it's unprovoked attack on South Korea on June 25, 1950.
MacArthur was the leader of the attack n North Korea and south korea civil war :)
No South Korea didn't envade North Korea. South and North splid up because of the alliance between North America and Russia was not good. North Korea is the one who attacks first all the time. We never started first. North Korea's ruler does not feed his citizens he uses the money for nuclear explosions.