South Korea's daily phone call to North Korea through the liaison office at Gaesong went unanswered this morning for the first time.
That's according to the Unification Ministry in Seoul, which said it was too early to make assumptions and would wait to see what happens in the afternoon call.
The two sides have spoken twice a day since the inter-Korean liaison office was set up in 2018.
The North threatened last Friday to shut down the office unless South Korea stops its people from using balloons to send anti-regime leaflets over the border.
Seoul's Defense Ministry says the inter-Korean military communication line, however, is still operating as normal.