Seoul: In a series of threats from North Korea with peace hopes and de-nuclearisation replaced by tensions, South Korea held an emergency security meeting on June 14 and said its military was on alert.

This comes amid growing concern in the divided peninsula which is faced with a new crisis more than two years after President Donald Trump and North Korean leader Kim Jong Un held an unprecedented summit in Singapore.

Kim’s influential sister warned on June 13 that the North would destroy an inter-Korean liaison office and unleash the army against the South due to anger over Seoul’s failure to stop activists from floating anti-regime leaflets across the border.

South Korea’s national security director, Chung Eui-yong, convened a video conference with other top security officials on June 14 morning to discuss the situation, which the government called “grave.”

The defence ministry in Seoul said it was closely monitoring North Korean military moves and maintaining a defensive posture “in preparation for all eventualities.” It also called on the North to stick to an inter-Korean military agreement aimed at restoring peace “and the prevention of accidental clashes.”

Kim Yo Jong, the North Korean leader’s sister who has recently been elevated in status as an official, said “it is high time to surely break with the South Korean authorities” and promised to “soon take a next action,” according to the state-run Korean Central News Agency.

“Before long, a tragic scene of the useless north-south joint liaison office completely collapsed would be seen,” she said, calling the South an “enemy.”

“Our army, too, will determine something for cooling down our people’s resentment and surely carry out it, I believe,” she said. “Rubbish must be thrown into dustbin.”

Kim didn’t specify a military action, and the North has not carried out previous threats, including a December promise to unveil a new “strategic weapon” that many predicted would be an intercontinental ballistic weapon.

The North Korean saber-rattling underscored the collapse of U.S.-led efforts to persuade the Kim regime to abandon its nuclear weapons, which reached a high point during the June 12, 2018, summit in Singapore.

But expectations of a breakthrough were dashed when Trump and Kim failed to reach a new deal in a second summit in February 2019 due to disagreements over the extent of sanctions removal in exchange for the dismantling of an aging nuclear facility.

North Korea, meanwhile, has continued to make progress in its nuclear weapons programme.