North Korea on Thursday described the knife attack on US Ambassador Mark Lippert in Seoul as "just punishment" for the US decision to push ahead with joint military exercises with South Korea.
"Just punishment for US warmongers," the official KCNA news agency said in the headline to a brief despatch which called the attack a valid "expression of resistance."
KCNA said the assault on Lippert by a knife-wielding activist reflected South Korean public opinion "which is critical of the US for causing a crisis of war on the Korean peninsula with the dangerous joint military exercises."
The annual joint drills, which always raise tensions with North Korea, began on Monday and involved thousands of South Korean and US troops.
The attacker, Kim Ki-Jong, reportedly told police that opposition to the exercises was the main motive for his action.
Meanwhile, the US ambassador was recovering from surgery after being slashed on his face and arm in Seoul on Thursday by a blade-wielding activist opposed to ongoing US-Korean military drills.
The United States condemned the "act of violence" which left the ambassador bleeding profusely and saw him rushed to hospital where his condition was described as stable after treatment by plastic and orthopaedic surgeons.
Witnesses described how a man armed with a 25-centimetre (10-inch) paring knife had lunged across a table and attacked Lippert at a breakfast function in central Seoul.
The assailant, dressed in traditional Korean clothes and identified as Kim Ki-Jong, 55, was immediately wrestled to the ground and taken into police custody.
During the assault, Kim screamed a slogan in favour of reunifying the divided Korean peninsula, and later shouted his opposition to joint US-SKorea military exercises that began on Monday.
He was a known political activist who had been handed a two-year suspended sentence in 2010 for throwing a rock at the then Japanese ambassador to Seoul.
Video footage showed Lippert, 42, being rushed from the breakfast event and bundled into a police car, one hand pressing a cloth to his bleeding right cheek, and his other hand and clothes smeared with blood.
One of the doctors who operated on the ambassador said if the deep cut on his cheek had been just a little lower it might have severed his carotid artery "which would have been life-threatening".
The hospital said there was some damage to sensory nerves in his right hand which was successfully treated during the surgery.
He was to remain in hospital for three to four days under observation.
The White House said President Barack Obama had called the ambassador and wished him a speedy recovery.
South Korean President Park Geun-Hye condemned the "intolerable" assault, saying it was tantamount to an attack on the South Korea-US military alliance. She vowed a "thorough investigation," while the foreign ministry said it would beef up security for foreign envoys.
A spokesman for the Korea Council for Reconciliation and Cooperation, which hosted the breakfast function, apologised for the lack of security at the event.
"This man suddenly jumped out of his seat when the breakfast was about to start at the table," the spokesman said.
"Other people tried to stop him but the situation unfolded too quickly," he added.
Kim runs a small activist group that pushes for reunification with North Korea and regularly organises protests against Japanese territorial claims to a group of small islands controlled by South Korea.
As he was being taken from the police station for treatment on an injured ankle, Kim told reporters he had been planning the attack for 10 days.
According to intelligence sources cited by the Yonhap news agency, Kim visited North Korea six times between 2006 and 2007 and tried to erect a memorial in Seoul to the late North Korean leader Kim Jong-Il after his death in late 2011.
Writing on the group's blog on Tuesday, Kim had complained that the joint US-South Korea drills were blocking dialogue between North and South Korea and preventing reunions for family members divided by the 1950-53 Korean War.
The annual exercises kicked off earlier this week, triggering a surge in tensions with the North.
Nearly 30,000 US troops are permanently stationed in South Korea and the United States would assume operational command in the event of an armed conflict with the North.
Lippert has proved a popular ambassador, tweeting regularly about his life in Seoul and setting up a tongue-in-cheek Twitter account for his dog, Grigsby.
His wife recently gave birth in Seoul and the couple gave their son a Korean middle name.