MELBOURNE, Australia — The U.S. Marine Corps has adjusted the number of F/A-18 Hornet squadrons on rotating deployments to Japan with the arrival of the F-35B Lightning II Joint Strike Fighter to that country, according to the Marine Corps deputy commandant for aviation.

Speaking to media at the Avalon Airshow in Geelong, Victoria, Australia, Lt. Gen. Jon Davis confirmed that the Marines will now have one F/A-18 squadron at Marine Combat Air Station Iwakuni on rotations under the Unit Deployment Program, or UDP, down from the previous two.

The UDP sees the rotational deployment of Marine air and ground units to the Western Pacific, or WESTPAC, for periods of approximately six months. While on rotation the Marines regularly take part in engagement with regional allies, with the Hornets taking part in exercises like Balikatan in the Philippines, Commando Sling in Singapore, and Cobra Gold in Thailand.

The Hornet UDP squadron will be part of Marine Air Group 12, 1st Marine Aircraft Wing for the duration of its rotational deployment, serving alongside Marine Fighter Attack Squadron (VMFA) 121, which is now based at Iwakuni with 10 F-35Bs since January, and VMFA-242 which operates the two-seat F/A-18D Hornet.

Another UDP AV-8B Harrier squadron operates out of Kadena Air Base in nearby Okinawa, and is assigned to the Okinawa-based 31st Marine Expeditionary Unit onboard the Navy’s sole forward-deployed landing helicopter dock during WESTPAC cruises.

Davis also touched on the continuing transition of Marine fast jet squadrons to the F-35 and the recent announcement of a slight deviation from the Marines’ latest Aviation Plan, which will now see F-18 squadrons get priority for transition to the F-35 ahead of their Harrier counterparts, noting that "our F-18 fleet is getting older faster, and the bottom line is we’ve got life on our Harriers and so we’re going to move our F-18s out faster than we are the Harriers."

He added that the "next three, maybe more, squadrons to transition to the F-35 will be all F-18 squadrons," with Miramar-based VMFA-225’s F/A-18Ds to take the place of Marine Attack Squadron 311’s Harriers in transitioning to the F-35B in fiscal 2020.

VMFA-225, which is the current UDP squadron in Iwakuni, was to have been the last operational Marine fast jet squadron to transition to the F-35B in fiscal 2030. Instead, it will now be the third in line to get the F-35 after VMFA-122 which is now in the process of transitioning to the F-35B, and VMFA-314 who will transition to the carrierborne F-35C planned for fiscal 2020.

Mike Yeo is the Asia correspondent for Defense News. He wrote his first defense-related magazine article in 1998 before pursuing an aerospace engineering degree at the Royal Melbourne Institute of Technology in Australia. Following a stint in engineering, he became a freelance defense reporter in 2013 and has written for several media outlets.

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