Police investigating the knife attack on the US ambassador to South Korea say a charge of attempted murder is likely to be laid.
Investigators are also probing possible links between the attack at a unification forum in Seoul and the attacker’s frequent visits to North Korea.
The South Korean Prime Minister has visited the ambassador, Mark Lippert, in hospital, where he needed 80 stitches after his face and hand were slashed.
Lee Wan-Koo told reporters afterwards that he hoped the alliance between the US and South Korea will be strengthened.
The assailant is described as a 55-year-old Korean nationalist who was protesting against annual US-South Korean military exercises that began last week.
In 2010 the man tried to attack the Japanese ambassador by throwing a piece of concrete.
North Korea praised the attack on Lippert as “deserved punishment” for the military exercises.