North Korea has threatened to permanently close a liaison office with South Korea, as Pyongyang grows increasingly upset by anti-North Korean leaflets coming from the South. Defectors and activists in South Korea have used balloons to send anti-North Korean messages across the border in recent weeks.

Kim Yo Jong, the sister of North Korean leader Kim Jong Un, has said Pyongyang could cancel a 2018 inter-Korean military agreement if the leaflets continue to reach North Korean territory. She also threatened to shut down a joint factory in the border town of Kaesong.

South Korea has said it would support new laws banning activists from flying the leaflets. An unidentified spokesperson of the North Korean Workers’ Party’s United Front Department has threatened Seoul with further measures.

"We will not hide that we for a long time have considered decisive measures to completely shut down all spaces of contact with the South and fundamentally eliminate the sources of provocations from the South," the spokesperson said. "The latest events have strengthened our conclusion that an enemy is just an enemy ... it is our determination to go as far as we can in a vicious cycle of confrontation."

Tensions have been high in the Korean Peninsula, with the two countries exchanging fire in the demilitarized zone (DMZ) separating the two nations in early May. A United Nations investigation into the incident determined both nations had violated the armistice that ended the 1950-53 Korean War. The exchange of gunfire did not result in any casualties. 

North Korea has also frequently derided military exercises between the U.S. and South Korea. The U.S. and South Korea announced they would postpone the annual drills due to the ongoing coronavirus outbreak.

North and South Korea are still technically at war, as the Korean War ended in a truce, not a peace treaty. One major point of contention is prisoners of war (POW), with Seoul frequently requesting repatriation of South Korean POWs from North Korea, and Pyongyang refusing to address the issue.