North Korea on Thursday called the knife attack on Mark Lippert, the U.S. ambassador to South Korea, a “just punishment for US warmongers,” according to the country’s official KCNA news agency. Lippert, who underwent a two-hour surgery following the attack, is in a stable condition, South Korean police and U.S. officials said.

Lippert was attacked by a knife-wielding man at a breakfast meeting in Seoul on Thursday. Authorities reportedly said that the attacker, identified as Kim Ki-Jong, a 55-year-old man, was heard making remarks against U.S.-South Korea military drills, which began last week and are expected to continue until the end of April. The man was arrested and authorities are considering whether to charge him with attempted homicide, a police official said, according to Reuters.

North Korea also expressed its anger over the joint military drills describing it as "unprecedentedly provocative in nature.” However, there was no confirmation if the attacker had any links to North Korea, BBC reported.

Graphic photos of the violent act released online show the 42-year-old Lippert with blood on his hand as he covers his face. He received 80 stitches to his face, but the cut did not affect his nerves or salivary gland, a hospital representative said, according to The Associated Press. An investigation is reportedly underway into the incident, following which the South Korean police provided additional security to the U.S. embassy in Seoul.

The attack was strongly condemned by the U.S. State Department, while South Korean President Park Guen-hye described the incident as an "attack on the South Korea-US alliance."

A police official, speaking on condition of anonymity, told AP that the attacker has a history of violence, and added that, in 2010, the suspect threw a piece of concrete at the Japanese ambassador in Seoul.