“The land clearing could be intended for both military and non-military aspects”, says Prof Kil Joo Ban of the Ilmin International Relations Institute, Korea University.
“It allows observatory posts to be easily established,” he says “for North Korea to monitor military activities in South Korea” and to spot “defectors who attempt to cross the border to South Korea.”
Is it to keep the North Koreans in?
Yes.
Edit: and more, possibly.
From the article: