A patrol plane unit of the Maritime Self-Defense Force has left on an intelligence-gathering mission that will help commercial ships with ties to Japan safely navigate waters in the Middle East.
Two P-3C aircraft departed from the Naha Air Base in Okinawa Prefecture on Saturday.
They will replace a unit engaged in anti-piracy missions off Somalia.
The operation in the Gulf of Oman, the northern part of the Arabian Sea, and the Gulf of Aden was approved by the Cabinet last month. The aircraft will begin gathering intelligence on January 20.
The unit is made up of about 60 personnel, and will be based in the East African nation of Djibouti.
Defense ministry officials say the unit will collect information on vessels that are acting suspiciously, including boats that have their Automatic Identification Systems turned off.
Separately, a destroyer is due to leave Japan in early February and will join the effort later in the month.