The U.S. ambassador in South Korea was wounded in a stabbing incident on Thursday, prompting Pyongyang to qualify the assault as a "knife attack of justice" reflecting "anti-U.S. sentiment," CNN reported.

A man shouting slogans against joint South Korean-U.S. war games slashed Mark Lippert's face and arm as the diplomat was about to give a speech at Seoul's Korean Council for Reconciliation and Cooperation, which advocates for the peaceful reunification of the peninsula.

Lippert was taken to a hospital, where he underwent more than two hours of surgery, the news channel noted. He received 80 stitches to his face and was reported to be in stable condition. Yonsei Severance Hospital's Jung Nam-shik said he expected the envoy to remain in the facility for the next three to four days.

The attacker, whom police identified as 55-year-old Kim Ki-jong, used a 10-inch kitchen knife to attack the ambassador, the Wall Street Journal detailed. The bearded man, dressed in a traditional Korean outfit, screamed calls for reunification between North and South Korea, the newspaper added.

Kim has a history of unpredictable behavior, CNN noted. He received a suspended two-year prison sentence in 2010 for throwing a piece of concrete at a Japanese ambassador to South Korea, the local Yonhap news agency recalled.

The Korean Central News Agency -- an official mouthpiece of the country's regime -- defined the attack as "just punishment for U.S. warmongers." South Korean President Park Geun-hye, meanwhile, strongly condemned it.

"This incident is not only a physical attack on the U.S. ambassador but an attack on the South Korea-U.S. alliance," she insisted. "And it can never be tolerated."

Seoul police said that the U.S. Embassy had not request special security for Thursday's event and that three of its officers had been posted at the entrance of the council's building. Twenty-five additional policemen had been on standby, authorities added.

Jang Yoon-seok told CNN affiliate YTN that she witnessed the attack on the U.S. envoy.

"When the man jumped on the ambassador, I stood up and jumped on the man, and they both fell on the ground," Jang recalled. "Luckily I got on top of the man's back and could press him to the floor. Then others came to hold him on the floor."