South Korea’s government said Wednesday that it will press charges against two activist groups that have been floating anti-Pyongyang leaflets and bottles filled with rice to North Korea for allegedly breaking the law by sending unauthorized materials to the rival nation.

The announcement by Seoul’s Unification Ministry came a day after North Korea announced it was cutting off all communication channels with South Korea over its inability to prevent North Korean defectors and other activists from flying the leaflets across the border.

Yoh Sang-key, the ministry’s spokesman, told reporters the two organizations to be charged had "created tensions between the South and North and brought danger to the lives and safety of (South Korean) residents in border areas."

Seoul’s pursuit of legal action against the groups is likely to trigger a debate over freedom of expression and whether President Moon Jae-in's liberal government is sacrificing democratic principles to keep alive his ambitions for inter-Korean engagement.

For years, activists have floated huge balloons into North Korea carrying leaflets criticizing leader Kim Jong Un over his nuclear ambitions and dismal human rights record. The leafleting has sometimes triggered a furious response from North Korea, which bristles at any attempt to undermine its leadership.

In 2014, soldiers exchanged fire after South Korean activists released propaganda balloons across the Demilitarized Zone, but no casualties were reported.

Yoh claimed that the two groups to be charged, led by North Korean defector Park Sang-hak and his brother Park Jung-oh, violated a law governing inter-Korean exchanges and cooperation by sending unauthorized materials to the North.

Park Sang-hak’s Fighters for a Free North Korea has launched balloons carrying anti-Pyongyang leaflets for years. Park Jung-oh leads the group Keun Saem, which on Monday unsuccessfully tried to float rice-filled bottles into North Korea from a border town before being blocked by South Korean police.

Neither group answered repeated calls for comment Wednesday.

The ministry didn’t say whether it was planning to take similar legal action against another group led by Lee Min-bok, also a North Korean defector who has been flying leaflets into the North for years.

Experts say North Korea’s move to cut off communication channels was likely more than just about leafleting as it comes after months of frustration over Seoul’s unwillingness to defy U.S.-led sanctions and resume inter-Korean economic projects that would breathe life into the North’s broken economy.

North Korea has suspended virtually all cooperation with South Korea in recent months amid a stalemate in larger nuclear negotiations with Washington.