SEOUL, South Korea (AP) — South Korea suspects that an unmanned drone that crashed on a frontline South Korean island was flown by rival North Korea.

The drone crashed on Baengnyeong island Monday when the two Koreas fired hundreds of artillery shells into each other’s waters in a flare-up of animosity over a long-disputed sea boundary between the countries.

The Blue House presidential office confirmed comments made by a spokesman to South Korean media Wednesday that Seoul officials think the drone is from North Korea based on a preliminary investigation. The spokesman didn’t elaborate.

South Korean media, citing unidentified military officials, reported that the drone was taking pictures of military facilities on South Korean islands near the Yellow Sea boundary with the North.

The Defense Ministry said it couldn’t confirm the reports.