North Korea blew up an inter-Korean liaison office on its side of the border on Tuesday, the South’s Unification ministry said, after days of increasingly virulent rhetoric from Pyongyang.

“North Korea blows up Kaesong Liaison Office at 14:49,” the ministry, which handles inter-Korean relations, said in a one-line alert sent to reporters.

North Korea is frustrated that the South has failed to offer an alternative plan to revive the US-North talks

Its destruction came after Kim Yo Jong, the powerful sister of North Korean leader Kim Jong Un, said at the weekend: “Before long, a tragic scene of the useless north-south joint liaison office completely collapsed would be seen.”

Earlier Tuesday, North Korea’s army said it was “fully ready” to take action against the South, included re-entering areas that had been demilitarised under an inter-Korean agreement.

“North Korea is frustrated that the South has failed to offer an alternative plan to revive the US-North talks, let alone create a right atmosphere for the revival,” said Cheong Seong-chang, a director of the Sejong Institute’s Center for North Korean Studies.