North Korea on Tuesday demolished an inter-Korean liaison office in a town on the border with South Korea in an escalation of tensions on the Korean Peninsula.
The North Korean state news agency, KCNA, reported Tuesday that the office was "completely ruined."
South Korea's vice unification minister, Suh Ho, who co-headed the liaison office, said the incident was "unprecedented in inter-Korean relations," calling it "a nonsensical act that should have not happened."
"We express deep regret and strongly protest against it," Suh said.
South Korea's Ministry of Defense said it was monitoring North Korean military movement around the clock after the demolition and maintaining a "resolute military posture."
"We are making full effort to manage the situation stably so that the situation does not escalate into a military crisis," the ministry said in a statement. "If North Korea carries out military provocation, our military will respond with powerful force."
North Korea's move to destroy the office, set up in 2018 in the North Korean border town of Kaesong to foster better ties with South Korea, coincides with the 20th anniversary of the first inter-Korean summit. Held June 13-15, 2000, the summit included a historic visit between South Korean President Kim Dae-Jung and the North Korean leader Kim Jong Il, and resulted in a joint peace declaration in which the two countries committed to promoting unification, and to humanitarian and economic cooperation.
Earlier this month, North Korea threatened to permanently shut the liaison office as it condemned the South for failing to prevent activists from sending anti-North Korean leaflets across the border. And just last week North Korea axed all communications with South Korea, citing the same anti-North Korean leafleting.
On Sunday, South Korea convened an emergency security meeting after North Korean leader Kim Jong Un's sister, Kim Yo Jong, one of his top aides, threatened military action against South Korea.
She also threatened to demolish the "useless" inter-Korean liaison office at the time.
Then on Tuesday, before South Korea's announcement that the liaison office was demolished, North Korea's KCNA reported that the Korean People's Army of North Korea had threatened to move back into recently demilitarized zones that had changed status under recent inter-Korean peace agreements as the country dialed up pressure on Seoul amid stalled nuclear negotiations with the Trump administration.
The general staff of the Korean People's Army said it is reviewing a ruling party recommendation to advance into unspecified border areas that had been demilitarized under agreements with the South, which would "turn the front line into a fortress."
'One of the greatest symbols of inter-Korean rapprochement since 2018'
The joint inter-Korean liaison office was meant to be a symbol of cooperation and a permanent channel of communication between the North and South Korea. It was established in 2018 amid a flurry of efforts to end the decades-old confrontation between the two rivals.
"It is significant from a symbolic point of view," said Ramon Pacheco Pardo, lecturer in international relations at King's College London. "The office was one of the greatest symbols of inter-Korean rapprochement since 2018. North Korea is now signaling that this period is over and it is going to take a more confrontational approach for the time being."
From a practical standpoint, he said, it will make lower-level inter-Korean communication more difficult because that's where inter-Korean conversations were taking place on a regular basis. But strategically the impact is minimal; there are many alternative ways to restore inter-Korean links when the time is right.
What is North Korea's motive for the escalation?
The latest escalation is a way for North Korea to express displeasure with the lack of progress in the removal of harsh U.S.-led international sanctions set up to push North Korea into handing over its nuclear arsenal, Pacheco Pardo said.
"North Korea knows that South Korea won't move ahead with full-scale economic cooperation as long as the sanctions regime remains in place," he said. "But ramping up tensions with the U.S. with an ICBM or nuclear test would be too risky."
Last week, North Korea said it was pulling away from its relationship with the U.S. saying there had been no actual improvement in ties. It has been two years since a historic handshake between Donald Trump and Kim Jong Un in Singapore and nearly a year after Trump took an unprecedented step onto North Korean soil. The Trump and Kim 2019 summit ended without a deal.
By increasing tensions with South Korea, Pacheco Pardo said Pyongyang can push Seoul to put pressure on Washington to resume diplomacy once the first wave of the coronavirus pandemic is over and, particularly, after the presidential election in November.
What will the North do next, and how will the U.S. respond?
The destruction of the liaison office shows that North Korea wants to escalate the crisis in order to compel Seoul into giving concessions, said Edward Howell, a researcher and North Korea specialist at the University of Oxford.
"The question remains as to how far the DPRK will have to escalate tensions before it gets any acceptable response, on the North's terms, from the South," Howell added, using the initials of the Democratic People's Republic of Korea.
Responding to NBC News' request for comment on the incident, a senior Trump administration official said they "remain in close coordination" with the South Korean officials.
And a U.S. State Department spokesperson told NBC that the United States "fully supports" the South's efforts on inter-Korean relations and urges North Korea "to refrain from further counterproductive actions."
But the U.S. reaction is likely to be capped at the usual condemnation, Howell said.
"The U.S. does not want to provoke North Korea to engage in further bellicose behavior with the upcoming presidential election, and especially given the increasingly threatening rhetoric from Pyongyang toward Washington, as of late," he added.
Pacheco Pardo said it wouldn't be surprising to see North Korea move its troops closer into the areas of the border that were previously demilitarized, perhaps even initiating a cross-border shooting.
"But I don't think that we will see a clash such as the 2010 Yeonpyeong shelling or the ROKS Cheonan sinking," Pacheco Pardo said, referring to two major escalations between the two countries a decade ago, the first when North Korea fired artillery shells at a South Korean island and the second involving the sinking of a South Korean naval vessel costing 46 lives. "That would compel South Korea to take a tougher response than it will with lower-level military actions."
As for South Korea, it's unlikely Seoul will move away from its current position of asking for diplomacy to resume and condemning Pyongyang's actions, Pacheco Pardo said.
"Unless North Korea takes a very serious action, it is very likely to maintain this approach," he said.