South Korea says it is analysing what it believes to be a North Korean drone that crashed on a border island shortly after an exchange of artillery fire with North Korea.
The drone crashed on Baengnyeong island on Monday afternoon.
It fell as the two Koreas traded fire into each other's waters in an incident Seoul says was provoked by the North.
South Korean authorities say a preliminary investigation has concluded that the drone came from the North.
"The relevant departments of the South Korean government have confirmed that North Korea is responsible for it," said South Korea's Unification Ministry spokesman Park Soo-jin.
A similar drone was found in Paju, just south of the demilitarised zone that separates the two Koreas, on 24 March, Yonhap news agency reported.
It was equipped with a a high-resolution camera and had taken pictures of military installations and South Korea's presidential compound, the agency said.
The two Koreas were divided at the end of the 1950-53 Korean War, which ended in an armistice rather than a peace treaty. They remain technically at war and the border is heavily fortified.
Monday's clash came after North Korea announced it would hold live-fire exercises in seven parts of the disputed western maritime border - a major flashpoint between the two nations.
South Korea says it returned fire after North Korean shells landed in its territorial waters. Hundreds of shells were fired, but all fell in the sea and nobody was hurt.
The exchange of fire happened days after North Korea tested medium-range missiles for the first time since 2009.
North Korea is the subject of multiple UN resolutions relating to its pursuit of nuclear weapons' development.