South Korea and the United States will kick off a major combined military exercise next week to beef up their joint defense, both sides said Monday, amid North Korea's hardening rhetoric adding to the prospects of it undertaking new provocations.

The annual Ulchi Freedom Shield exercise based on an all-out war scenario is set to take place from Aug. 21-31, featuring various contingency drills, such as the computer simulation-based command post exercise, concurrent field training and Ulchi civil defense drills.

In the lead-up to the drills, Pyongyang has ratcheted up tensions with leader Kim Jong-un having recently called for a "drastic boost" in the country's missile production capability and for war contingency preparations in an "offensive" manner.

"Ulchi Freedom Shield 23 is designed to be a tough and realistic exercise to strengthen the combined defense posture and alliance response capabilities based on scenarios that reflect diverse threats within the security environment and lessons learned from recent wars and conflicts," the Joint Chiefs of Staff said in a press release.

The exercise also includes drills on responses to cyberattacks and terrorism, it added.

Some 30 allied field drills are slated to take place during this year's UFS, compared with 25 during the springtime Freedom Shield exercise this year and 13 in last year's UFS, according to a JCS official.

Aside from South Korean and US participants, personnel from member countries of the UN Command will join the exercise. The UNC is a key enforcer of the armistice that halted the fighting in the 1950-53 Korean War.

The Neutral Nations Supervisory Commission, an observer of the armistice, will also attend the drills. (Yonhap)