A Seoul court on Friday handed a 12-year prison sentence to a South Korean man who slashed and seriously injured the U.S. ambassador during a March forum.

Kim Ki-jong was convicted of attempted murder, assaulting a foreign envoy and obstruction, according to court spokesman Joon Young Maeng. Both Kim and the prosecution have one week to determine whether to appeal, Maeng said. Prosecutors had previously asked for a 15-year prison term.

Kim slashed Mark Lippert during a breakfast forum in Seoul, leaving deep gashes on the envoy's face and arm. Lippert was treated for five days at a Seoul hospital.

Kim has described himself as an anti-U.S. activist. He told police that his assault was meant to protest U.S.-South Korean military drills but that he did not intend to kill the ambassador.

The drills, which are meant as a deterrent against North Korean attack, are a major source of friction on the Korean Peninsula. Pyongyang says they are meant as practice for a northward invasion to topple the dictatorship that has ruled the country since its founding in 1948.