A government investigation finds that disruptions in signal reception by South Korea’s global positioning systems (GPS) on the west coast in August were traced to the North Korean border city of Gaeseong.

The Korea Communications Commission made the announcement Wednesday, adding that the investigation was conducted after receiving reports from domestic mobile operators about disruptions in GPS reception.

Defense Minister Kim Tae-young told a parliamentary inquiry of the government Tuesday that North Korea appears to have equipment capable of disrupting GPS reception in areas within a radius of up to 100 kilometers.

He said that the government is working to devise countermeasures against such occurrences in the future.

The South experienced sporadic interruptions in GPS reception for several hours in areas along the west coast for three days starting August 23rd.