The US and South Korean militaries have started a joint exercise aimed at addressing possible emergencies on the Korean Peninsula. They are also on high alert, as North Korea could take countermeasures in protest.

The regular Ulchi Freedom Shield military exercise began in South Korea on Monday. It is scheduled to end on August 29.

This year's edition involves 48 field training sessions and multi-domain drills, including cyberdefense activities. One main focus of the exercise is to enhance the capability of the two militaries to deter and defend against North Korea's weapons of mass destruction.

South Korean media outlets say that, during the exercise, the government will for the first time conduct at least one drill designed to simulate a North Korean nuclear attack.

On Thursday, citizens will participate in a drill whereby they will practice evacuating in response to an air raid warning.

The North Korean Foreign Ministry's Institute for American Studies issued a statement on Sunday. It denounced the military activities as "war drills for aggression."

The statement said, "The more frequently the US and its vassal countries commit collective military provocations, the stronger the deterrence of justice for neutralizing the threat...will become."

In August of last year, North Korea launched two short-range ballistic missiles on the eve of the last day of the US and South Korea's joint exercise. Pyongyang said the firing was a response to air force drills carried out by the US and South Korea.