North Korea has blown up the liaison office between the two Koreas, following days of tension between the neighbors.

South Korea’s Unification Ministry sent out a one-line message on Tuesday afternoon: “North Korea blows up Kaesong Liaison Office at 14:49.”

North Korea was angered by the floating of anti-regime leaflets from the South by former defectors. It has also apparently tired of diplomacy. In recent days, the regime publicly said that dialogue with the U.S. is pointless, and that South Korea should stop its call for denuclearization of the Korean peninsula.

In a series of mounting reactions, North Korea closed the Liaison Office and stopped responding to scheduled twice-daily hotline phone calls between the two. In the last couple of days, it upped the ante and threatened a military response.

The military options available that would have stopped short of a full armed conflict were considered to be cross-border shelling at the places where leaflets had been released; demolition of the symbolic Liaison Office; or a partial reoccupation of the Demilitarized Zone that runs the length of the border between the two countries.

North Korean leader Kim Jong-un has been largely away from public view over the last month; however, his sister Kim Yo-jong has stepped in as spokesperson and appeared to warn of imminent military action.

“Our army, too, will determine something for cooling down our people’s resentment and surely carry [it out], I believe,” she said.

After Kim Yo-jong darkly warned on Saturday, “Before long, a tragic scene of the useless North-South joint liaison office completely collapsed would be seen,” observers speculated that the North could either fire ammunition across the Demilitarized Zone (DMZ) at the place where the balloons had been released, or demolish the Inter-Korean Liaison Office at Kaesong.

Kim Yo-jong also said that dissidents living in the South should “pay the dearest price for their crimes.” Kidnapping and abductions have been used previously by the North.

Observers had speculated that June 14 or 15 would be obvious dates for such action. The former date was the birthday of U.S. President Donald Trump, while the latter is the 20th anniversary of the first inter-Korean summit meeting.

The South Korean government under South Korean President Moon Jae-in held an emergency security meeting on Sunday to review the tense situation.

With the hotline cut, South Korea has fewer options to dial down the situation, which may make a military response more likely. But at least one observer said the escalation of tension had been carefully stage managed.

“In some way, this all reminds me of Iran’s response to the U.S. assassination of Qasem Soleimani. Everyone knew an Iranian strike was coming. It was well telegraphed. The Iranians were able to take a kinetic retaliatory action and minimize the chance it would escalate into war,” said commentator Chad O’Carroll, who serves as CEO of consultancy Korea Risk Group. “I conclude the North Koreans are communicating threats publicly for similar reasons.”