The South Korean army and police conduct a joint live anti-terror drill at a bank branch in Daegu on Monday. (Yonhap)

The Ulchi Freedom Shield exercise of the military forces of South Korea and the United States jointly kicked off on Monday with South Korean civilians, with the primary focus on addressing North Korea's nonkinetic operations, such as public opinion warfare, cyberattacks and the spread of fake news.

The annual summertime joint military exercise that runs through Aug. 29 is the third such exercise since President Yoon Suk Yeol took office in May 2022, as Pyongyang increasingly blends unconventional war tools with nuclear missile threats, according to Seoul.

Alongside the military exercise, a four-day civil defense exercise involving some 580,000 civilians from about 4,000 institutions also began Monday, to involve a civil defense drill Thursday during which people here at 2 p.m. will be advised to move to one of some 17,000 shelters following an evacuation siren. Traffic controls will come into effect.

In this vein, Yoon on Monday stressed South Korea's capacity to fend off social unrest in the wake of Pyongyang's propaganda operations and incitement at a Cabinet meeting held at his office, followed by a meeting of the National Security Council he presided over.

"As we can see from the war in Ukraine and the conflicts in the Middle East, war can break out at any time," Yoon said. "Furthermore, the nature of warfare has also changed a lot from in the past."

In his remarks there, Yoon called for a defense readiness posture of both the government and the military, while reiterating the threat of "antistate forces" conducting covert operations in South Korean society, which mirrored his Liberation Day speech urging people not to be deluded by false propaganda and "pseudo-intellectuals" circulating fake news.

President Yoon Suk Yeol salutes to the national flag as he presided over a Cabinet meeting in his office in Seoul Monday. (Presidential office)

"Everywhere in our society are anti-state forces active in secret operations and threatening our freedom and democracy," he said, without specifying who he was referring to.

"North Korea will capitalize on (antistate forces) in the early stage of warfare to instigate national confusion and divide public opinion using violence, public opinion rigging, propaganda and incitement," he added, calling on the nation to devise ways to fight and find solutions for such confusion and division.

An official from the presidential office said on condition of anonymity that any of these instigators posing a threat to freedom and democracy should be deemed anticonstitutional.

Yoon has remained an unpopular president, as his approval rating has hovered in the low-to-middle 30 percent range for most of his term dating to May 2022. The conservative president's job approval rating hit its lowest point in two months at 30.7 percent in the third week of August, according to a Realmeter poll Monday.

Yoon said this year's Ulchi Freedom Shield will focus on "practicing comprehensive measures" to respond to Pyongyang's low-level "gray-zone provocations" such as hacking attacks, trash-carrying balloons and GPS jamming attacks.

"Hybrid warfare is being waged as a military strategy combining conventional warfare with irregular warfare, cyberwarfare and psychological warfare with the generation of fake news influencing public opinion and sentiment," Yoon said.

President Yoon Suk Yeol (fifth from left) convenes a National Security Council meeting in Seoul Monday. (Presidential office)

The exercise -- involving both computer-simulated war games and field-based outdoor drills -- will also focus on response measures against hypothetical attacks on roads, telecommunications infrastructure, utilities or nuclear power plants.

"Now that the roles in the military and civilians are blurring against this backdrop, we need to come up with a national war readiness posture where all parties concerned gather strength."

According to South Korea's Joint Chiefs of Staff on Sunday, the government will participate in a drill against an invasion scenario by North Korea involving a nuclear attack, for the first time in South Korea's history.

Forty-eight joint field-based drills between South Korea and the US involving live-fire drills will take place during the exercise, outstripping 38 last year. Yoon said the expanded outdoor drills in the exercise will "enhance the combined capabilities" of the two countries' military forces and "contribute to boasting the South Korea-US military alliance."