The North has expressed its anger about the balloons, and the South has attempted to stop the activists.

Since a 2018 thaw, the long-standing rivals had been making efforts to improve ties and maintain dialogue.

But the relationship appeared to have deteriorated rapidly in the past week.

The North on Friday blew up the Inter Korean Liaison Office, on its side of the border, which was set up two years ago to ensure regular dialogue between the two countries.

Wednesday marks the anniversary of the start of the Korean War. Analysts believe Pyongyang is intentionally ratcheting up the tension to increase its bargaining power and force new talks.

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