An explosion during an artillery exercise near the eastern border with the Democratic People's Republic of Korea (DPRK), on Friday injured six South Korean soldiers and killed a seventh, a South Korean army official said.
In addition to South Korea and USA forces, UN Command forces from seven sending states including Australia, Canada, Columbia, Denmark, New Zealand, the Netherlands and the United Kingdom will participate in this annual exercise.
Fears about North Korea's missile and nuclear weapons programmes have grown in recent weeks, leading to a promise of "fire and fury" from U.S. President Donald Trump for North Korea if the country continues to threaten the U.S.
The DPRK has denounced it as a dress rehearsal for northward invasion, though the two allies insisted on the nature of defense of the annually-held computer-assisted simulation exercises.
This incident comes as South Korea prepares to engage in the annual Ulchi Freedom Guardian exercises with the USA starting August 21.
Jeong, who will become the second Air Force officer to take the highest active-duty post if he receives a parliamentary nod, said South Korea will not seek to bring back U.S. tactical nuclear weapons, which Washington withdrew from the Korean Peninsula in 1991.
South Korean military said a probe into the cause of the incident is still under way.
South Korea is banned from developing nukes on its own under the Nuclear Non-proliferation Treaty - which it signed in 1975.
North Korea has fired missiles and taken other steps in response to the war games in the past.
"We want to use diplomacy. We have to do our best to prevent North Korea from declaring (full nuclear armament)", the Air Force general told the lawmakers.