North Korea is fortifying the border at the only point of the demilitarized zone (DMZ) where North and South Korean forces stand face-to-face.

North Korean men were spotted digging a trench and planting trees at the Joint Security Area (JSA), where a soldier crossed in a dramatic defection on November 13.

In video footage, he was seen driving a jeep towards the border before getting stuck in a ditch and then making a dash across the demarcation line to the South. He was chased by four North Korean border guards who shot him five times.

Read more: A North Korean soldier who defected is still haunted by dreams of his homeland

A diplomatic delegation including Marc Knapper, chargé d’affaires at the U.S. Embassy in Seoul and the top U.S. diplomat in the country until an ambassador to South Korea is officially appointed, visited the area on Wednesday.

The U.S. Embassy in Seoul declined a Newsweek request to speak to Knapper, but the diplomat posted a picture on Twitter showing five North Korean men busy digging in the ground, closely guarded by soldiers. “Was at JSA today, the North Koreans have planted two trees and are digging a trench at the spot where their soldier crossed the MDL,” he wrote.

“The workers were being watched very closely by the KPA guards, not just the two in the photo, but others out of shot behind the building,” one of the diplomats who visited the JSA told Reuters on condition of anonymity due to the sensitivity of the situation.

The daring defection has not yet been mentioned in the state-controlled North Korean media, but according to a South Korean intelligence source, Pyongyang ordered the removal and replacement of between 35 and 40 border guards posted there for failing to prevent the defection. The guards are usually handpicked for assignment at the border to ensure ideological commitment to the regime.

Seoul’s spy agency also told lawmakers top North Korean military officials Hwang Pyong So and Kim Won Hong were punished for “impure attitude” following an inspection led by Choe Ryong Hae, the vice chairman of the ruling party’s Central Committee, whose son is reportedly married to the country’s leader Kim Jong Un’s younger sister and who used to lead the military bureau before Hwang replaced him in May 2014.

The North Korean defector is now recovering from his injuries following two rounds of surgery and was transferred from the intensive care unit to a general ward of the Ajou University Hospital, South Korean news agency Yonhap reported on Friday. South Korean government agencies are now discussing who will foot the bill for his medical expenses, which is expected to come to around $100,000.

“As the medical costs are unprecedentedly high, if relevant ministries make an official request for the issue, we plan to decide who will foot the bill through consultations,” said Lee Eugene, vice spokesperson at the South Korean unification ministry, quoted in Yonhap.

The 24-year-old, who was only identified by his surname Oh, regained consciousness, is in stable condition and talked to the doctors about his enjoyment of South Korean girl bands’ pop music and American movies and tv shows.