These two pics show the time I went to the Korean DMZ back in 1986. The first was taken in the building used for negotiations between the North Koreans and U.N. Forces, as represented by the US. The table stands directly astride the border between North and South Korea. You can see through the window on the other side, NK guard on the left and an American soldier on the right. Although, we could technically stand in North Korea INSIDE the building, if any of us were to violate the border OUTSIDE, it would be an international incident.
The second picture depicts the focal point of an actual international incident between North Korea and the US. In 1976, A tree which was ordered pruned by US authorities because it obstructed a view of the area. North Koren soldiers brutally attacked the worker crew and two American soldiers were killed.
This incident almost culminated in an escalation of hostilities. The story of the incident is told here:
http://www.pbs.org/frontlineworld/stories/northkorea/1976.htmlI have to say, it was an interesting trip, to say the least.