SEOUL • South Korea yesterday warned North Korea to stop disrupting Global Positioning Satellite (GPS) signal reception which it said forced some fishing boats to return to port, and vowed to act if it continued, amid heightened tension over the North's weapons tests.
Seoul said it had traced signals that disrupted GPS reception to four regions in the North close to the rivals' armed border on Thursday and again yesterday.
South Korea has been on high alert against possible cyber attacks from the North, after its angry rhetoric threatening war and further nuclear and rocket tests in response to new sanctions imposed last month by the UN Security Council.
"The disruptive activity is clearly a flagrant act of provocation that violates the armistice and International Telecommunication Union (ITU) rules and we urge that it stop immediately," the South's Defence Ministry said in a statement.
ITU is the United Nations agency overseeing global telecommunication networks and technologies.
The North would pay a price if it continued, the South said.
The reclusive North and rich, democratic South are technically still at war since their 1950-53 conflict ended in an armistice, not a peace treaty.
Seoul said the National Security Council met to discuss the GPS disruption and demanded the North "immediately stop the dangerous and reckless activity".
Hundreds of South Korean fishing vessels off both coasts including 70 of the 332 that had left the eastern port of Sokcho yesterday returned early after suffering GPS malfunctions, media reports said, citing the coast guard.
There have been no reports of air traffic disruptions, the South's Transport Ministry said.
In 2010, the South's Defence Minister warned that North Korea had obtained a Russian-made jamming device capable of disrupting guided weapons systems.
Two years later, during a similar period of cross-border tensions, the South said North Korean jamming activities had forced hundreds of South Korean civilian aircraft and ships to use back-up navigational equipment to avoid compromising safety.
Pyongyang dismissed the allegations as "sheer fabrication".
Last month, Seoul's spy agency said Pyongyang had stepped up cyber attack efforts against the South, including a bid to break into a subway control system that was foiled.
South Korea has previously blamed the North for cyber attacks against its nuclear power operator.
The United States accused the North of a cyber attack against Sony Pictures in 2014, forcing the studio to cancel the release of a comedy based on the fictional assassination of the country's leader. The North denied responsibility.
REUTERS, AGENCE FRANCE-PRESSE