A Seoul court Friday handed down a 12-year-prison term to the 55-year-old man who attacked the top U.S. envoy to South Korea earlier this year, but acquitted him of charges of violating the National Security Law.

The Seoul Central District Court found Kim Ki-jong, who was accused of attacking Amb. Mark Lippert with a knife at a breakfast function in Seoul on March 5, guilty of attempted murder, violence against a foreign envoy and business obstruction.

The attack left the ambassador with deep gashes on his face and arm that needed more than 80 stitches.

"Kim seems to have had a strong will to attack the victim, choosing a knife to repeatedly slash the part of the body that had a direct connection with life," Judge Kim Dong-ah said.

The court, however, acquitted Kim of charges of violating the country's anti-North Korea law which prohibits citizens from supporting or praising the North.

Prosecutors earlier said that Kim attacked the envoy following the North's accusation that South Korea-U.S. joint military exercises are war rehearsals for an attack against the North, adding that books and other materials confiscated from Kim's home support North Korea's strategy to communize South Korea.

"While some of the defendant's arguments coincide with that of the North, such as opposing the military exercises, they are ideas that have been often claimed by the academic circles and civic groups in the country," Judge Kim said, adding the claim does not pose a direct threat to the country.

Regarding the books and documents confiscated from Kim's house that supported the North, the court said the amount was only marginal.

"Kim had been studying reunification at graduate school.

Considering the huge amount of materials on the two countries' traditional cultures found at his place, Kim does not seem to have kept the pro-North Korean documents to benefit the North," Judge Kim added.

After the sentence was delivered, prosecutors said they will appeal the acquittal on the breach of National Security Law. (Yonhap)