North Korea on Thursday threatened to turn the South’s presidential office of Cheong Wa Dae into a “sea of fire” in a statement by its military denouncing Wednesday’s military exercise on Yeonpyeongdo and Baengnyeongdo.

South Korea carried out the exercise on the border islands on the first anniversary of the North’s artillery attack on Yeongpyeongdo that killed two marines and two civilians.

The belligerent rhetoric is some of the strongest in recent months. It is the first time for it to issue such a strong warning against Cheong Wa Dae. In February, Pyongyang threatened to turn Seoul into a sea of fire, criticizing the annual South Korea-U.S. military exercises.

“Our revolutionary military power is completely ready to respond to any military provocations,” said the Supreme Command of the North Korean People’s Army in a statement carried by the official Korean Central News Agency.

“Should (the South) fire even a single shot into our sea, air or land, it should bear in mind that the sea of fire will lead to a sea of fire in Cheong Wa Dae, which will then spread to devastate the stronghold of the traitors’ group.”

After the exercise on the border islands, “Uriminjokkiri,” a website run by the North’s Committee for the Peaceful Reunification of the Fatherland, also issued a statement criticizing the exercise.

The threat comes as Seoul has softened its stance on the North in efforts to enhance ties that went sour in the wake of the two deadly attacks last year that killed 50 South Koreans.

In March 1994, a North Korean representative first threatened to turn Seoul into a sea of fire during a working-level inter-Korean meeting at the inter-Korean border village of Panmunjeom.

Following the hostile comment, the South referred the North as the “main enemy” in its 1995 defense whitepaper, which was taken out of the 2004 paper when the mood was more conciliatory.

North Korea has long disputed the NLL, seeking to make the South’s frontline areas around the border a disputed region. The North, which contends the border should be redrawn further south, claims that the waters near the frontline islands are part of its territory.

By Song Sang-ho (sshluck@heraldcorp.com)