SEOUL, South Korea -- South Korean prosecutors on Thursday asked for a 15-year prison term for the man they say slashed the U.S. ambassador during a breakfast forum in March.

Prosecutors made the request at the end of the trial of Kim Ki-jong, who faces charges of attempted murder, assaulting a foreign envoy and obstruction, according to the Seoul Central District Court.

The court will issue a verdict Sept. 11, a court official said on condition of anonymity citing official rules.

Police said he attacked Ambassador Mark Lippert with a knife, inflicting deep gashes on his face and arm. Lippert was treated at a Seoul hospital for five days.

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Police said Kim told investigators he chose Lippert as a target to highlight his opposition to springtime U.S.-South Korean military drills, which North Korea calls an invasion rehearsal.

Anti-U.S. activists such as Kim have long opposed such military training between Seoul and Washington and the presence of 28,500 U.S. troops in South Korea, blaming them for persistent animosities on the Korean Peninsula.

Seoul and Washington have said their drills are defensive in nature and that the U.S. military presence is aimed at deterring potential aggression from North Korea.

During Thursday's trial, prosecutors said Kim clearly intended to kill Lippert because of the force of repeated downward stabbing motions on a critical body part, according to Yonhap news agency. Kim's defense lawyer said that he only tried to inflict harm on Lippert without intending to killing him, according to Yonhap.

Court officials said they couldn't confirm the report.