South Korea says it has confirmed that three crudely built drones found crashed on its territory in recent months originated in North Korea.
Defense Ministry spokesman Kim Min-seok said U.S. and South Korean officials made the determination using the drones' GPS data.
"After analyzing the flying route of the three drones, it was confirmed that all three of them were programmed to be launched from North Korea and were to return to the North, which is clear scientific evidence proving that the North had sent them," said Kim.
Kim said sending the drones was a "clear military provocation" that violates the countries' armistice and non-aggression agreements.
The aircraft were discovered after crashing in three different locations near the North-South border between late March and early April.
One of the drones was discovered with pictures of sensitive government locations, including the South Korean presidential Blue House.
Pyongyang has firmly denied sending the planes. It says Seoul is making up the story in order to make it look bad.
The drones are not technically advanced and were unable to deliver weapons, but their presence raised questions about Seoul's air defenses.
The North's state media boasted about what they call the country's "super precision drone planes," which have also been featured in military parades.
Seoul has said that certain unspecified parts of the drones came from other countries, including China.
The North Korea Tech website recently discovered pictures of a Chinese drone that looks very much like the ones found crashed on South Korean territory.
China has not commented on the finding.