North Korea has blown up and destroyed an inter-Korean liaison office in its border city of Kaesong on Tuesday.
The site was opened in 2018 and aimed reducing tensions between the two Koreas.
It comes as North Korea's army warned it is "fully ready" to send troops into the demilitarised zone (DMZ), in response to defector groups in the South sending propaganda leaflets into the North.
According to the state media, the Korean People's Army (KPA) said it is studying an "action plan" to reenter zones and "turn the front line into a fortress".
"Our army will rapidly and thoroughly implement any decisions and orders of the Party and government," the KPA said in a statement.
Tensions have risen over the leaflets, with Pyongyang threatening to cut all inter-Korean ties.
Meanwhile, Seoul's defence ministry urged the North to abide by the 2018 agreement while adding that their military is being readied to "respond to any situation".
The US and Iran failed to reach an agreement to end their war despite lengthy talks that concluded on Sunday in the Pakistani capital Islamabad, jeopardising a fragile ceasefire.
At least 30 people were killed on Saturday in a stampede at the Laferriere Citadel in the northern countryside of Haiti, authorities said, warning that the death toll could rise.
A cyclone battered New Zealand's North Island on Sunday, cutting power to thousands of residents and forcing hundreds to evacuate, as officials warned conditions would worsen through the day.
Negotiations between the United States and Iran appeared to have concluded for now, Iran's government has announced early on Sunday, after a series of talks in Pakistan to end the six-week war between Washington and Tehran.
Costa Rica on Saturday has received the first group of migrants from other countries deported from the United States under an agreement signed in March between the two countries, local authorities said.