“An Air Force aircraft, deployed in Poland under NATO’s Assurance Measures operation, inadvertently entered Finland’s airspace [Monday] later that morning,” the Air Force said in a statement.

According to the note, the mission was taking place in the Baltic Sea between Estonia and Finland, when the P-3C CUP+ crew carried out a “route correction and failed to prevent the radius of return exceeding about 0.3 nautical miles (500m) the limit of the air space.”

The Air Force regretted what happened, explaining that it was not a premeditated action, but rather a “consequence of the flight manoeuvre.”