The soldiers went missing during a military drill during an exercise at the General Silvestras Žukauskas training ground in Pabradė, a town located less than 10km (6 miles) from the border with Belarus.
Lithuanian and foreign troops, along with helicopters from the air force and the state border guard service, were deployed to search for the soldiers.
Except the bodies weren’t in the vehicle. That would suggest that the soldiers were either killed or abducted, and the vehicle was hidden in the water. That doesn’t entirely rule out an accident, but it seems less likely.
I could totally see the US blaming europeans not Russians, if this was proven a GRU operation.