http://www.youtube.com/watch?v=Xkz6TYjD5_w (South Korean Special Force)
http://www.youtube.com/watch?v=pQ8scwHOjPE (North Korean Special Force)
All Korean men must go to military service. It is unchangeable destiny for all Korean men, whether they like it or not. Men must serve the military because S. Korea and N.Korea is divided in two. Even though there are U.S. troops to support military power, it doesn't mean S.Korea can only rely on U.S. military force. Therefore S.Korea continuously does mandatory draft from S.Korea and spent big amount of GDP on National Defense as well.
On the other hand, North Korea has more soldiers than S.Korean soldiers and U.S. soldiers combined. Also the number of tanks, missiles, ships, and other weapons are out numbered S. Korean military. Therefore keeping U.S. force on S.Korean soil is significant but there were some Anti-American solidiers movement continously occured in S.Korea that about couple years ago, George W. Bush decide to pulled out some military personnel in S.Korea and rather put more efficient weapons like missiles.
Overall military power of S.Korea is 9 th in the world, where as N.Korean military power is 4 th in the world. Compare to size of nation, N.Korean military is very powerful. In N.Korea about 70% of whole population involved with some what military work including teenagers and women.
Some say the reason why S.Korea keeps S.Korean military is when war begins then S.Korean force can maintain the situation about 2 weeks which is about U.S. aircraft carrier will reach to the Korean sea board.
military comparison between North and South in 2000