The North Korean soldier who was shot while defecting to South Korea on Monday suffered massive internal damage, the surgeon leading his treatment said on Wednesday.
The soldier shot and injured by the North Korean side while defecting from a military post in front of Panmungak, the main building managed by North Korea in the Joint Security Area, the JCS said in a statement.
The military drills come amid U.S. President Donald Trump's visit to Asia, which has been dominated by discussions over the North Korean nuclear threat.
During his trip, Trump struck a tough tone on North Korea, calling for an end to its nuclear program and saying "we hope to God we never have to use" the military strength the U.S. has on the Korean Peninsula.
Suh Wook, chief director of operations for the South's Joint Chiefs of Staff, told lawmakers that North Korea fired a total of about 40 rounds in a shooting that his office suggested started while the soldier was in the jeep.
In a letter to UN Secretary-General Antonio Guterres, seen by Reuters, North Korean UN Ambassador Ja Song Nam said the United States was "running amok for war exercises by introducing nuclear war equipment in and around the Korean Peninsula".
While on average more than 1,000 North Koreans defect to South Korea every year, most travel via China and it is unusual for a North Korean to cross the land border with South Korea.
The solider was found beneath a pile of leaves on the southern side of the JSA and South Korean troops crawled there to recover him.
There was no armed conflict between the two sides, the military said.
At Panmunjom, once an obscure farming village inside the 2 1/2-mile-wide DMZ that separating the rivaling countries, North Korean soldiers wearing lapel pins with the images of late North Korean leaders often use binoculars to monitor visitors from the South.
Panmunjomis where an armistice was signed to pause the Korean War.
In 1976, North Korean soldiers axed two American army officers to death and the United States responded by flying nuclear-capable B-52 bombers toward the DMZ in an attempt to intimidate the North.
The Joint Security Area was the site of some bloodshed during the Cold War but there hasn't been major violence there in recent years.
He didn't elaborate on what "the last" might be, but North Korea has launched ballistic missiles that have the potential to strike the US mainland, and it recently conducted its largest-ever underground nuclear explosion.
Monday was the first time since 2007 a North Korean soldier had defected across the JSA.