South Korea's military said Thursday it is not investigating the alleged flight of South Korean drones over North Korea's capital earlier this month, describing it as a matter to be clarified by the North. Last Friday, North Korea accused the South of sending drones over Pyongyang three times this month in what it described as a "serious provocation." South Korea has declined to confirm whether it sent the drones. When asked if the military was looking into the alleged flights, Joint Chiefs of Staff (JCS) spokesperson Col. Lee Sung-jun said there was no need for an investigation just because of the North's claim. "I don't know why the JCS should be investigating drones that appeared over Pyongyang," Lee said in a briefing. "This is something that should be clarified by North Korea." On Tuesday, Kim Yo-jong, the influential sister of the North's leader, claimed her country had secured "clear evidence" that the South's military was responsible for the flights but did not present any of it. Separately, Lee said the military was keeping in mind the possibility of Pyongyang using its video footage to report on the reclusive country's explosions of inter-Korean land routes Tuesday. Earlier Thursday, the North's state media released photos of parts of the western Gyeongui and eastern Donghae routes being blown up, with one of the images appearing to be similar to the JCS footage. The detonations came after North Korea said last week it would permanently block its border with South Korea and build front-line defense structures. Source: Yonhap News Agency