Seoul has rejected North Korea's demand to conduct a joint investigation of drones that crashed on South Korean soil.
North Korea denied responsibility Monday, accusing the South of fabricating evidence. The North's powerful National Defense Commission then proposed a joint investigation of all cases that Seoul blames Pyongyang for, including the sinking of the Navy corvette Cheonan in 2010 that killed 46 South Korean sailors.
South Korea held the North responsible following an international probe, but the North still denies involvement.
The commission asked South Korea's top presidential security adviser Kim Jang-soo to lead the South Korean team.
The Defense Ministry here in an interim report last Friday presented additional evidence like engine capacity, fuel-tank sizes, flight hours and designs that further point to Pyongyang as having sent the drones.
The first suspected North Korean drone was discovered on March 24th in Paju, north of Seoul and close to the inter-Korean border, the second a week later near a maritime border between the two Koreas and the third on Sunday about 300 km east of Seoul.