South Korea reported further antagonism by Pyongyang Friday, including jamming of GPS signals and a surface-to-air missile launch, a news report said Friday.
The jamming signal, which was also detected on Thursday, had increased in strength and affected 58 planes and 52 boats in South Korea, Yonhap News Agency reported, citing the science and communications ministry. It was first noticed in early March.
Two planes reported the jamming, but no flights were disrupted.
"If the North's GPS jamming results in real damage to airplanes or ships, we will make the North pay a due price," ministry spokesman Moon Sang Gyun was quoted as saying.
The areas affected are near the inter-Korean border, and the signals were too weak to cause wider disruption in South Korea, the ministry said.
Also on Friday, North Korea launched what the South Korean military said was a surface-to-air missile towards the sea off the eastern coast of the peninsula.
The missile flew some 100 kilometres before dropping into the sea, Yonhap said.
Tensions have been high on the peninsula since the beginning of the year, when Pyongyang conducted a nuclear test and long-range rocket launch, prompting increased international sanctions.