By Rachel Lee

North Korea is stepping up its effort to tighten its border security following the defection of a soldier to South Korea via the Joint Security Area (JSA).

The North has installed a gate on the so-called 72-Hour Bridge across which the soldier drove a military jeep toward the JSA, according to an intelligence source, Saturday. Border guards are placed at the checkpoint _ presumably in an attempt to check the identities of soldiers and allow passage only to those whose identities are confirmed.

On Nov. 13, the North Korean soldier drove the jeep across the bridge, but the vehicle broke down near some JSA buildings, so he got out and ran south across the Military Demarcation Line (MDL). Four North Korean guards engaged him with direct fire of about 40 gunshots, and the soldier was hit five times before collapsing.

The source said the North has also placed more machine guns at the JSA guard post.

The possession of a machine gun inside the JSA is a violation of the 1953 Armistice Agreement, but Pyongyang has recently deployed such heavy weapons.

As part of its efforts to prevent other soldiers from defecting, the country dug a one-meter deep trench at the spot where the soldier got out of the vehicle.

Marc Knapper, the acting U.S. ambassador in Seoul, tweeted a photo this week showing North Koreans digging the trench and apparently planting trees in the supervision area.

"The North Koreans have planted two trees and are digging a trench at the spot where their soldier crossed the MDL," Knapper tweeted Nov. 22, referring to the JSA.

After the defection via the JSA, North Korea replaced all border guards there.

An intelligence source said last week the North changed all of the guards, after they failed to prevent the soldier's defection. Commanders of the unit and other senior officials may also have been punished, the source said.

It is said there were between 35 to 40 North Korean guards in the JSA.

The young soldier, known only by his family name Oh, is now in stable condition after undergoing two major operations, Lee Cook-jong, a surgeon at Ajou University Hospital, said.

The U.N. Command released a dramatic video clip of the soldier's run for freedom while being shot at by his former comrades, last week.

（作者：汽车配件）