Turkish fighter jets conducted a total of five unauthorized flights over the eastern Aegean in under 40 minutes on Tuesday morning, according to Greek authorities.
The first violation of Greek airspace came at 9.47 a.m. and involved a pair of Turkish F-16s flying at 24,000 feet above Oinousses and Panagia.
The Croatian Defence Ministry said on Monday that a military helicopter had crashed into the Adriatic Sea that morning, killing the pilot.
It said the air force OH-58 D Kiowa helicopter crashed between the island of Zlarin and the coastal town of Zablace near Sibenik. The pilot was confirmed dead while the search for the second crew member was ongoing.
He told CNN that the FBI's evidence-gathering team was on site and assisting local authorities with the investigation.
The Federal Aviation Administration and National Transportation Safety Board are investigating the crash and will determine the official cause. The FBI is also assisting the investigation, a standard practice.