The US and South Korea have commenced Ulchi Freedom Guardian 2017, a computer-simulated defense exercise for combat troops to be held from 21 to 31 August.
The exercise seeks to improve readiness, protect the region and maintain stability on the Korean peninsula.
More than 17,500 US service members and 3,000 troops from installations outside South Korea have been deployed to take part in the exercise.
The ten-day exercise will also witness participation from South Korean military forces and government employees.
In addition, Ulchi Freedom Guardian 2017 will feature United Nations Command forces from seven nations, namely Australia, Canada, Colombia, Denmark, New Zealand, the Netherlands and the UK.
Commenting on the exercise, US Defense Secretary Jim Mattis said: "This right now is an exercise to make certain that we're ready to defend South Korea and our allies over there.
"Because of the specific circumstance, we want it to be a command post-heavy, command post exercise."
The observers from the Neutral Nations Supervisory Commission will monitor the exercise to ensure it complies with the 1953 armistice agreement.
Training exercises such as Ulchi Freedom Guardian are carried out as part of the Mutual Defense Treaty signed between South Korean and US in October 1953 and in accordance with the armistice.
A DoD official said: "These exercises also highlight the longstanding military partnership, commitment and enduring friendship between the two nations, help to ensure peace and security on the peninsula, and reaffirm US commitment to the alliance.”
Image: US and South Korean soldiers conduct operations in the Combined Joint Task Force Elimination Headquarters during 2016's Ulchi-Freedom Guardian. Photo: courtesy of US Army / Major Ryan Donald.