North Korea has been jamming the GPS signals of "hundreds" of civilian aircraft over the past week, according to officials from the South. Transport Ministry assistant director Yang Chang-Seang told the AFP that 337 aircraft have reported GPS signal failure since Saturday, and commission deputy director Lee Kyung-Woo said that the jamming had been traced in Kaesong's direction. Kaesong is a city six miles north of the Korean Demilitarized Zone, and is host to an collaborative industrial park where several South Korean companies employ workers from the North. Yang says that the jamming poses "no threat to navigational safety," and the planes can use different systems such as inertial navigation and VHF omni-directional range (VOR).
North Korea has not admitted any part in the incident, which comes amid heightened tensions on the Korean peninsula following the death of Kim Jong-Il in December and the subsequent ascension to power of his son Kim Jong-Un. It's unclear what the North might hope to achieve by disrupting civilian craft, but the South's former defence minister Kim Tae-Young warned back in 2010 of a vehicle-mounted GPS jamming device supplied by Russia that could potentially be used to disable weapons and other military equipment. That year, the device was blamed for malfunctioning GPS units on various naval and civilian craft.