The South Korean government’s latest move to ban anti-Pyongyang leaflet launches by civic groups following North Korea’s strong complaints has stirred up controversy over the freedom of expression.

Seoul’s Unification Ministry revealed Thursday a plan to legislate a law banning the leaflet launches, describing them as “tension-building acts,” with the presidential office Blue House vowing stern responses if the launches pose a danger to national security.

The leaflet campaigns, the latest of which took place Sunday, involve sending across the border balloons filled with leaflets carrying messages critical of North Korean leader Kim Jong-un and relief goods -- $1 bills and USB sticks containing popular South Korean TV programs -- for residents in the North.

A senior official at Human Rights Watch criticized Seoul for seeking to stop the “harmless” campaign.

“The Ministry of Unification should not violate the right to freedom of expression just because Kim Jong-un’s sister demands they do so,” Phil Robertson told The Korea Herald in an email.

He said the launches were an example of freedom of expression that should be “celebrated rather than limited,” adding Seoul was “bending over backwards” to relinquish rights the South Korean people fought long to secure.

Local experts joined the criticism.

“The question we need to ask here is this: Is the legal ban the best path available to limit the freedom of expression the Constitution guarantees?” Kim Sang-kyum, a professor who teaches constitutional law at Dongguk University, told The Korea Herald.

The professor noted the government could limit individual freedoms when there is a threat to state security or welfare, but even in those cases it should stick to measures that incur the least infringement upon people’s rights.

“I’m not 100 percent certain whether the two conditions -- existence of a threat to security or welfare and the rule of least infringement -- are being met here,” Kim said.

Another professor of constitutional law, who spoke on the condition of anonymity due to the topic’s sensitivity, said: “Forcing essentially everyone in the country not to engage in the campaign could go beyond what’s necessary.”

The Unification Ministry said the leaflet campaign endangers lives and properties of those living near the border, with its minister saying Friday, “My understanding is that the majority of citizens would also oppose the campaign that brings tension hikes.”

The heads of regional governments bordering North Korea were in agreement with the ministry as well, the ministry added, quoting them as saying, “Leafleting is an irresponsible act that goes against the wishes of border residents who seek safe and peaceful lives.”

Despite growing opposition from conservative fronts fiercely championing the freedom of expression, the ruling Democratic Party of Korea, which controls the 300-seat parliament, is determined to pass a bill to legalize the ban.

By Choi Si-young (siyoungchoi@heraldcorp.com)