Marine Fighter Attack Squadron 121, an F-35B squadron with 3rd Marine Aircraft Wing, departed Marine Corps Air Station (MCAS) Yuma, Arizona, on 9th January transferring to MCAS Iwakuni, Japan. Iwakuni is the first location to receive the Marine Corps' F-35B.

VMFA-121, formerly a 3rd MAW F/A-18 Hornet squadron, was re-designated as the Corps’ first operational F-35 squadron, VMFA-121, in November 2012. The Commandant of the Marine Corps publicly declared VMFA-121 initial operating capability on 31st July  2015.

In December 2015, VMFA-121 employed its F-35Bs in support of Exercise Steel Knight. The exercise is a combined-arms live-fire exercise which integrates capabilities of air and ground combat elements to complete a wide range of military operations in an austere environment to prepare the 1st Marine Division for deployment as the ground combat element of a Marine Air-Ground Task Force.

In October 2016, a contingent of Marine Corps F-35Bs, pilots and maintainers participated in Developmental Test III and the Lightning Carrier Proof of Concept Demonstration aboard the USS America. Data and lessons learned laid the groundwork for developing the concepts of operations for F-35B deployments aboard U.S. Navy amphibious carriers, the first two of which will take place in 2018.

The U.S. Navy announced in October that the multi-purpose amphibious assault ship USS Wasp (LHD 1), which has been modernised to accommodate the Marine Corps F-35B, would move from Norfolk, Va., to Sasebo, Japan, in support of VMFA-121.