June 9 (UPI) -- Concern is growing in South Korea after the military said a North Korean drone equipped with a Japanese camera was found near the demilitarized zone.
The drone was not captured on surveillance radar and was instead reported by a local resident in Inje County, Gangwon Province, Yonhap news agency reported Friday.
The drone was identical to an unmanned aerial vehicle that had crashed on a remote South Korean island in March 2014, near the maritime border with the North.
Both drones have a 2.45-meter wingspan, and a built-in Nikon D800 DSR camera, according to the report.
Experts say South Korea's self-developed radars have difficulty detecting small drones that fly at an altitude of 1-2 miles.
Seoul military radars failed to track as many as three incoming North Korean UAVs at the border in 2014. South Korean residents reported the three drones after they crash-landed in different parts of the country.
South Korea also reported an unidentifiable object that flew across the DMZ from North Korea on May 23.
Yonhap later reported more than 10 UAVs had been deployed by Pyongyang at the time. South Korea's air force in response scrambled F-15K fighter jets.
The UAVs were captured on radar in May, but the latest incident is a cause for worry.
South Korea's army operates low-probability-of-intercept radar, the TPS-830K. Its ability to detect smaller aircraft is limited.
Seoul's air force deploys a gap filler radar system that can detect low-altitude aircraft like the AN-2, but its ability to detect drones in mountainous regions is also restricted.
South Korea had plans to purchase about 10 RPS-42 Tactical Air Surveillance Radar Systems from an Israeli firm, but no new radar systems have been deployed, according to Yonhap.