Prosecutors on Sunday sought arrest warrant for seven university students who broke into the US ambassador’s residence in Seoul on Friday, as the police strengthened security measures around the area.

The seven are among 17 members of a university students’ association who entered the US ambassador’s residence and two who attempted to enter. All 19 were taken into police custody on Friday for trespassing or attempting to trespass on the residence of US Ambassador to South Korea Harry Harris. 

At around 2:50 p.m. on Friday, 17 students used ladders to climb the wall and enter the compound to protest the United States’ reported requests to increase Korea’s share of the cost of maintaining the US troops here.

Police released 10 of the 19 on Saturday, but requested arrest warrants for the other nine. In response, the prosecution filed requests with the court for arrest warrants for seven of the nine protesters.

After concerns emerged that it had been too easy for the protesters to enter the embassy, the police deployed 80 police officers to guard the area, according to the Seoul Metropolitan Police Agency. Two conscripted police platoons and 30 police officers will guard the area at night, the agency said.

Previously, two platoons each consisting of some 30 conscripted policemen had guarded the residence.

The police will install a hotline with the US embassy, and will simplify procedures to deploy officers to the site in case an incident like this happens again, the agency added.

“We have reinforced the security measures by deploying the police squad and increasing the number of officers. We will also come up with measures to prevent similar cases from happening again,” an official from the police agency said.

The US Department of State issued a statement Saturday expressing regret over the incident and urged the South Korean government to strengthen efforts to protect all diplomatic missions in the country.

“We note with strong concern that this is the second instance of illegal entry into the Ambassador’s residential compound in 14 months,” the statement said.

In September last year, a Chinese national of Korean ethnicity was arrested after she was found trespassing at the ambassador’s residence.

Harris expressed his appreciation for the Korean police on Saturday, also mentioning last year’s trespassing incident.

“Big shout out to Embassy guards & Seoul Metro Police Agency for responding to protesters who breached perimeter around my residence,” he said via Twitter, adding, “2nd incident in 13 months in Heart of Seoul.”

The students staged the protest to criticize the US for demanding greater contributions from Korea for the maintenance of the 28,500 US troops stationed here.

Upon news of the warrant requests for the students, Jinbo Corea, a Seoul-based civic organization, and the unification department within the Korean Confederation of Trade Unions held a press conference Saturday to declare the protesters’ innocence.

“The US ambassador’s actions threaten Korea’s economic sovereignty and rob our taxpayers’ money,” one of the press conference organizers said.

While Seoul agreed to pay 1.04 trillion won ($871 million) under this year’s defense cost-sharing pact, there are concerns here that the US may be seeking a substantial hike in Seoul’s contribution, possibly as much as $5 billion -- almost a sixfold increase.

The two sides are expected to hold the second round of talks for next year’s cost-sharing deal from Tuesday to Thursday in Hawaii.

By Jo He-rim (herim@heraldcorp.com)