Seoul, Aug 12 (IANS): South Korea and the United States will begin a major combined military exercise next week to strengthen their joint defence readiness in the face of evolving North Korean military threats, the Joint Chiefs of Staff (JCS) said on Monday.

The annual Ulchi Freedom Shield (UFS) exercise based on an all-out war scenario is set to take place from August 19-29, featuring the main computer simulation-based command post exercise, concurrent field training and civil defence drills, Yonhap news agency reported.

During the exercise period, the government-led Ulchi civil defence drill will involve a scenario simulating a North Korean nuclear attack for the first time, a source said, while the joint military exercise will not incorporate such a scenario.

The allies' exercise comes amid growing concerns over Pyongyang's continued weapons development push, highlighted by its launches of 37 ballistic missiles this year alone, and heightened cross-border tensions from the North's recent trash-balloon campaign.

The allies said this year's exercise will reflect threats across all domains, including those posed by North Korean missiles, GPS jamming and cyberattacks, as well as lessons learned from recent armed conflicts.

"In particular, the ROK-US alliance will further strengthen its capability and posture to deter and defend against weapons of mass destruction," they said in a release. ROK stands for the Republic of Korea, the South's official name.

The exercise will be similar in scale to the previous year, involving some 19,000 South Korean troops, JCS spokesperson Colonel Lee Sung-jun said in a joint briefing. It will also include 48 field training events, such as amphibious landings and live-fire drills.

Lieutenant Colonel Ryan Donald, spokesperson of the US Forces Korea (USFK), said UFS is one of the largest exercises in the Indo-Pacific region while declining to comment on whether US strategic assets will be deployed during the exercise period.

The North has long denounced the allies' joint exercises as a rehearsal for an invasion against it and has a track record of staging weapons tests in response. South Korea and the United States have rejected the accusation, describing their drills as defensive.

JCS Chairman Admiral Kim Myung-soo said the North is likely to use the allies' exercise as a pretext to conduct provocations, and ordered troops to retaliate immediately during a visit to a western frontline unit, his office said.

Meanwhile, Lee confirmed only the Ulchi civil defence drill, scheduled from August 19-22, will incorporate training on responding to a North Korean nuclear scenario.

It will be the first time the government-led exercise will reflect a scenario simulating damage from a North Korean nuclear weapon, the source said, compared with last year's edition that focused on preparing for a nuclear crisis.

Late last month, USFK Commander General Paul LaCamera said the allies would not incorporate such a scenario in the UFS exercise, despite expectations it would feature the nuclear crisis dimension for the first time.

The allies have been pushing to enhance their joint readiness against the North's nuclear threats, conducting their first-ever tabletop exercise on integrating South Korean conventional forces with US nuclear capabilities earlier this month.

Aside from South Korean and US troops, personnel from several member countries of the UN Command (UNC) will join the exercise. The UNC was an enforcer of the armistice that halted the fighting in the 1950-53 Korean War.