Swedish daily Dagens Nyheter revealed that an anonymous drone entered the Utö training area whilst exercise BALTOPS was taking place last month.
Radosław Drożdżewski (User:Zwiadowca21) (Own work) [CC BY-SA 4.0], via Wikimedia Commons
Finnish, Germany, British, Swedish and U.S. troops were carrying out amphibious landing at the island when Swedish Defense Forces detected the drone in the area.