The U.S. Ambassador to South Korea was attacked Thursday morning by a man opposed to the joint military drills being conducted by the United States and South Korea.

As U.S. envoy Mark Lippert was about to deliver a speech, the man slashed the ambassador's face and arms, according to CNN. Lippert was in stable condition. Lippert underwent two hours of surgery and has 80 stitches in his face alone. Dr. Jung Nam-shik at Yonsei Severance Hospital said ippert will likely remain in the hospital for three or four more days.

The suspect has been identified as 55-year-old Kim Ki-Jong, according to CNN. Kim has a history of erratic, violent behavior. In 2010, Kim received a suspended two-year sentence for throwing a chunk of concrete at the Japanese Ambassador to South Korea.

"This incident is not only a physical attack on the U.S. ambassador, but an attack on the South Korea-U.S. alliance and it can never be tolerated," South Korean President Park Geun-hye said.

The event Lippert was attending was organized by Korea Council For Reconciliation and Cooperation, which advocates peace between the north and south. The suspect was a member of the council.

Kim ran from another table to the right of the ambassador, according to CNN, wielding a 10-inch wooden-handled knife and yelling what sounded like anti-U.S. opinions.

"When the man jumped on the ambassador, I stood up and jumped on the man and they both fell on the ground," a witness, Jang Yoon Seok told CNN affiliate YTN. "Luckily I got on top of the man's back and could press him to the floor. Then others came to hold him on the floor."

The suspect was rolled in a blanket and carried out of the Sejong Cultural Institute in central Seoul while he yelled, "The South Korea-U.S. military drills must stop."

The laceration on the ambassador's face runs from his right cheekbone to his lower jaw. It is about four inches long and an inch deep, but there is no damage to his facial nerve reported. Lippert also received five slashes in his left arm and hand, but doctors do not expect any permanent damage to the ambassador's arm function.

"The ambassador was very calm. People around him were taken back but he was very calm," said Dr. John Linton, according to CNN. "He was speaking with his doctor on what to do. It was surprising."

Lippert is a longtime friend of President Barack Obama and was nominated to serve as ambassador by Obama last year. National Security Council spokeswoman Bernadette Meehan said that Obama called Lippert "to tell him that he and his wife Robyn are in his thoughts and prayers, and to wish him the very best for a speedy recovery."

Lippert took to Twitter on Thursday afternoon to report on his condition. He Tweeted, "Doing well & in great spirits! Robyn, Sejun, Grigsby & I - deeply moved by the support!," referring to his wife, his son and his dog. "Will be back ASAP to advance US-ROK alliance." The Korean characters, according to CNN, mean, "Let's work together."