North Korea flew five drones across the border into South Korea, entering South Korean airspace in an area near the border.
The South Korean military attempted to shoot down the drones using jets and helicopters but was unsuccessful.
Instead, the drones were used as a way for North Korea to spy on South Korea and potentially launch attacks.
The incident has caused increased tensions between the two Koreas, as North Korea has conducted many missile tests this year.
The South Korean military sent surveillance planes to North Korea to photograph its military installations.
Experts believe North Korea is working to improve and refine its weapons while also trying to get the US to ease sanctions through future negotiations.