Attacks or attempts at attacking foreign envoys here have taken place in the past, raising concerns that better security may be needed to protect foreign dignitaries following the knife attack on U.S. Ambassador to Seoul Mark Lippert Thursday.

South Korean police did not deploy security personnel to the conference as the ambassador is not on the government’s list of protected officials.

In accordance with the regulations on the protection of key officials, the South Korean president, Supreme Court chief justice, speaker of the National Assembly and important scientists are among the tens of individuals on the security list.

Foreign diplomats in Seoul must request police protection to be provided related services, police said.

In 2010, Kim Ki-jong, the culprit behind the knife assault against Lippert, was sentenced to two years in prison with a three-year probation after throwing chunks of concrete at then-Japanese Ambassador Toshinori Shigeie at a conference in Seoul. He was not hurt but a female junior diplomat who was translating beside the envoy was treated for a minor injury.

But the latest incident sent shockwaves through the country not only due to its sheer cruelty but also the fact that South Korea is known for its relatively low crime rate.

A series of incidents took place in the 1980s when anti-U.S. sentiment snowballed in the wake of a democracy uprising, with students occupying or setting fire to U.S. cultural institutes in Seoul, Busan, Gwangju, Daegu and elsewhere.

Such provocations have died out and demonstrations have become more peaceful as democracy matured and the economy thrived.

In another unusual case, activists hurled plastic water bottles and trash at the vehicle of then-U.S. Ambassador Kathleen Stephens at a rally in downtown Seoul in 2011 during which they unveiled a new monument dedicated to former President Rhee Syng-man.

In 2011, a Chinese national named Liu Qiang was sentenced to 10 months in jail for throwing four Molotov cocktails at the Japanese Embassy building here, prompting Seoul’s dilemma in the face of a diplomatic spat between Beijing and Tokyo over his repatriation.

“I understand that Lippert has been guarded properly until now, but it seems that the situation today was inescapable. We plan to reinforce security and vigilance for other diplomatic missions here,” an official at the Foreign Ministry said, requesting anonymity due to the sensitivity of the matter.

By Shin Hyon-hee and Jeong Hunny (heeshin@heraldcorp.com)