Few situations would cause more anxiety to the general public than one in which anyone can be attacked suddenly in a defenseless state by a total stranger -- for no reason and regardless of time and place. Such a horrible crime recently occurred on a Seoul street in broad daylight.

A 33-year-old man surnamed Cho stabbed one pedestrian to death and injured three others in an alley in a shopping district near Sillim Station in Seoul at around 2 p.m. on July 21. The rampage happened for three or four minutes. All of the victims including the young man in his 20s who lost his life were utter strangers to the perpetrator.

"Everything about me was so bad for a long time," Cho reportedly testified in a pre-trial detention hearing, "I'm just a no-good bum." He is also said to have told the police earlier that "I live an unhappy life so I wanted to make others as unhappy as myself, and I committed the crime in rage." No matter what excuses he makes, it is a brutal, unpardonable crime to kill or injure innocent strangers to vent hatred of unspecified persons. It is hardly understandable from the viewpoint of common sense that he committed the crime for such reasons. However, the more worrisome problem is that such tragedies can occur anytime.

In May, 23-year-old Jung Yu-jung murdered a woman in her 20s, driven by the urge to kill. They had not met each other at all, but Jung planned carefully to select a target and killed her in their first encounter.

Cho's unprovoked attack is also similar to the so-called "Busan roundhouse kick case" where the assailant followed a young woman of no prior acquaintance to her apartment. He knocked her down with a roundhouse kick to the back of her head and kept assaulting her in the hallway of her apartment.

Unprovoked murder and assaults by a perfect stranger are nothing new, but law enforcement authorities need to pay attention to the recent surge in violent crimes of opportunity. The motives of unprovoked crimes are opaque and their targets are chosen instantly so prevention and anti-crime preparation become all the more difficult.

According to the National Police Agency, crimes of opportunity have increased each year, and more than 80 percent of them were serious offenses such as murder and infliction of injury. These offenses include unprovoked stranger assaults. The agency has formed a task force to respond to such stranger crimes, but it has neither presented related statistics nor announced preventive measures yet.

Justice Minister Han Dong-hoon visited the scene the day after the Sillim stabbing rampage, and said "I'll think more about managing and overseeing psychopaths."

It does not seem easy to draw up brilliant measures right now. Finding out psychopaths and managing them possibly violates human rights. Considering the characteristics of indiscriminate stranger violence, a limited effect is inevitable from such policing measures as strengthening patrols and crime prevention campaigns. Also, further debates are needed over whether Cho can be established as a psychopath.

Unprovoked strange attackers have nothing to do with victims. Be that as it may, the crimes are not without motives or backgrounds.

Experts see unprovoked attacks as a socio-pathological phenomenon. The likelihood of crime occurrence has risen, influenced by mounting resentment over the hyper-competition and winner-takes-all culture and deepening polarization. The chance of expressing anger violently is said to go up in a situation where an offender has few persons to communicate with and where social systems fail to reduce dissatisfaction. To add insult to injury, more and more young people are being detached from their families and the society.

Dissatisfied "lone wolves" who straggled in the competitive society are prone to commit unprovoked stranger attacks out of despair. Now is the time to ponder macro-solutions together.