South Korea has said the joint drill, due to finish on Tuesday, was in response to North Korean nuclear and missile provocations and to show any such developments by Pyongyang can be repelled with "overwhelming force".
It said an investigation into Monday's event was ongoing.
"Currently, the North Korean troops are conducting ordinary field exercises", a South Korean military official said in a briefing, according to Yonhap.
According to the South Korean military there was no exchange of fire across the border, and the UNC statement stressed that no South Korean or U.S. forces were harmed in the incident, which happened in broad daylight around 4:00pm. Panmunjom is a village situated on the borders of North and South Korea.
Seoul, South Korea -A North Korean soldier was shot by his former comrades while defecting to South Korea across the demilitarized zone, Seoul's Joint Chiefs of Staff said in a statement Monday. It wasn't immediately known how serious the soldier's injuries were or why he chose to defect.
South Korean military said there was no armed conflict after the incident, but they are "increasing alertness" for a possible provocation from North Korea.
Supreme Court to hear crisis pregnancy centers' appeal
The Supreme Court found that women have a constitutional right to an abortion in the landmark 1973 case Roe v. The court said the law is "ideological in intent" and violates doctors' free-speech rights.
North Korea is often described as a Communist state, but its official ideology is Juche, or "self-reliance", a political system that blends nationalism and Marxist economics.
Most flee across the North's porous frontier with China and then move on to a third country to seek passage to South Korea. More than a million mines are buried inside the zone.
"A" was detained after a member of the public alerted South Korea's military to his presence in the area.
The North Korean ambassador accused the council of "turning a blind eye to the nuclear war exercises of the United States who is hell bent on bringing a catastrophic disaster to humanity".
North Korean soldiers wielding axes hacked two USA soldiers to death at Panmunjom in a 1976 brawl over an attempt to trim a tree there.
US President Donald Trump hinted last week that his administration is now in contact with North Korea. All three "reaffirmed their commitment to maintaining maximum pressure on North Korea in an effort to denuclearize the Korean Peninsula", the White House said.