North Korea destroyed a building that was a key symbol of inter-Korean cooperation, in an apparent attempt to exert pressure on Seoul and Washington for their stalled dialogue.
Smoke was seen billowing from the inter-Korean liaison office building in the border city of Kaesong on North Korea's side of the demilitarised zone yesterday, following the sound of an explosion.
North Korea's state-owned Korean Central News Agency later confirmed that the facility had been "tragically ruined with a terrific explosion".
The move, the culmination of a series of threats and harsh rhetoric, prompted a stern warning from South Korea's presidential Blue House that it would "strongly respond if North Korea takes any action that further worsens the situation".
Japanese Prime Minister Shinzo Abe said Japan would analyse the situation and respond in close coordination with South Korea and the United States.
"Japan is hoping that there will be no further escalation in tensions between North and South Korea," he added.
China's Foreign Ministry spokesman Zhao Lijian did not refer directly to the explosion but voiced the hope for peace and stability on the Korean peninsula during his daily briefing. China, one of the isolated nation's few allies, has considerable sway over it.
The liaison office was opened in September 2018 to support inter-Korean exchanges after an agreement was signed between South Korean President Moon Jae-in and North Korean leader Kim Jong Un during their first summit in April that year.
In January, both sides agreed to close the office due to concerns over the coronavirus spreading. North Korea also barred entry to all foreigners.
Last Saturday, Mr Kim's powerful sister, Yo Jong, warned that Seoul would soon see "a tragic scene of the useless North-South joint liaison office completely collapsed".
The regime has been dialling up rhetoric against the South in anger over propaganda balloons released by North Korean defectors criticising their former leader.
President Moon on Monday urged Pyongyang to leave the door open for dialogue, and said both sides must abide by the peace deals he and Mr Kim signed in 2018.
But yesterday, the North Korean military warned it would send troops "into the zones that had been demilitarised under the North-South agreement, turn the front line into a fortress and further heighten the military vigilance against the South".
South Korea will try to de-escalate the tension by talking to North Korea. But it will be a challenging task because North Korea apparently wants to run the course of its version of 'fire and fury' towards South Korea to the fullest.
DR LEE SEONG-HYON of the Sejong Institute think-tank, warning that inter-Korean ties have "entered a dark, bottomless pit" with the destruction of the liaison office.
While it did not give details, there are only two joint economic zones - Mount Kumgang resort and Kaesong Industrial Complex, where the liaison office is located.
The state-owned Rodong Sinmun newspaper also warned of a "lightning strike on South Korean authorities as punishment and exterminate this scum", referring to the defectors who released the propaganda balloons.
Experts said Pyongyang's hardline tactics could be aimed at exerting pressure on Seoul and Washington to force them to resume stalled nuclear talks, which have taken a back seat as Mr Trump focuses on re-election.
Professor Leif-Eric Easley of Ewha Womans University said Pyongyang could be trying to decouple the Seoul-Washington alliance by making things "politically inconvenient for both Trump and Moon", such that the US would leave Seoul to deal with Pyongyang on its own.
"Kim Jong Un wants Moon to cancel military exercises and circumvent sanctions to provide the North with economic benefits," he said. "Eventually, North Korea will challenge the US directly and demand sanctions relief to de-escalate a manufactured crisis."
Prof Easley added that Mr Kim "sees little to lose" by pressuring South Korea, and that the regime will continue to escalate tensions even if Seoul responds with restraint.
Dr Lee Seong-hyon of the Sejong Institute think-tank warned that inter-Korean ties have "entered a dark, bottomless pit" with the destruction of the liaison office.
"South Korea will try to de-escalate the tension by talking to North Korea. But it will be a challenging task because North Korea apparently wants to run the course of its version of 'fire and fury' towards South Korea to the fullest."
MAY 3: North Korea fires multiple shots towards a South Korean guard post at the demilitarised zone separating the two Koreas, prompting the South to retaliate.
MAY 8: North Korean military lashes out at a May 6 exercise by the South Korean air force, calling it a grave provocation that violated inter-Korean agreements for reducing tension.
JUNE 4: North Korean leader Kim Jong Un's sister Yo Jong threatens to scrap a military agreement with the South and shut down all cross-border exchanges, unless Seoul takes action against anti-Pyongyang propaganda balloons sent across the border by North Korean defectors.
JUNE 9: North Korea refuses to answer calls from the South after vowing to cut all phone lines, calling the South an "enemy".
JUNE 11: North Korea accuses the United States of interfering in inter-Korean affairs, warns of "unbearable bad things".
JUNE 13: Ms Kim Yo Jong warns that Seoul will soon witness a "tragic scene of the useless North-South joint liaison office completely collapsed". North Korea also says it has lost all confidence in the South and warns of "regrettable and painful" times ahead.
JUNE 14: South Korea convenes an emergency security meeting, urges the North to keep peace deals.
JUNE 15: South Korean President Moon Jae-in urges Pyongyang to leave the door open for dialogue.
JUNE 16: North Korea warns of "lightning strike" on the South and blows up inter-Korean liaison office in Kaesong.