The U.S. Marine Corps declared initial operational capability (IOC) of the F-35B Lightning II on July 31, a milestone that represents official recognition the vertical takeoff and landing variant of the fighter is ready for combat. Marine Fighter Attack Squadron 121 (VMFA-21), based at Yuma, Ariz., is the first squadron to begin operations with the fifth-generation fighter.

The Marines are the first of three U.S. services to reach IOC with the fighter, 14 years after the Pentagon awarded a system development and demonstration contract to Lockheed Martin under the Joint Strike Fighter program. Marine Commandant Gen. Joseph Dunford, who will take over as the new chairman of the Joint Chiefs of Staff in September, made the eagerly anticipated declaration.

“I am pleased to announce that VMFA-121 has achieved initial operational capability in the F-35B, as defined by requirements outlined in the June 2014 Joint Report to Congressional Defense Committees,” Dunford stated. The squadron, which completed a five-day operational readiness inspection earlier this month, “is capable of conducting close air support, offensive and defensive counter air, air interdiction, assault support escort and armed reconnaissance as part of a Marine Air Ground Task Force, or in support of the Joint Force,” he added.

VMFA-121 enters operational status with 10 F-35Bs equipped with “Block 2B” software. The Air Force plans to declare IOC with the F-35A conventional takeoff and landing variant in late 2016; the Navy is targeting 2018 for the F-35C carrier variant. The latter two services will begin operations with more evolved and capable software than the Marines now have.

Praise for the Marines’ accomplishment poured in from the U.S. military and industry. “On 31 May 2013, the U.S. Marine Corps sent a letter to Congress saying they would reach F-35B initial operating capability between July and December 2015,” noted Air Force Lt. Gen. Christopher Bogdan, who has been outspoken in his role as F-35 program executive officer. “The fact the Marines reached IOC at the beginning of their six-month window is a testament to the professionalism and dedication of the entire F-35 enterprise. The U.S. Marine Corps decision to make the F-35B ready for combat is a significant event for the F-35 program.”

Pratt & Whitney and Rolls-Royce, which supply the F135-PW-600 engine and lift fan propulsion system of the F-35B, said the Marines’ stated IOC goal in 2013 “became a rallying point for the propulsion team and the entire F-35 enterprise. And now, thanks to the unyielding commitment and leadership of the Marines, that objective has been achieved.”

Marine Attack Squadron 211, an AV-8B Harrier squadron, is scheduled to transition to the F-35B in Fiscal Year 2016, which begins in October. Marine Fighter Attack Squadron 122, an F-18 Hornet squadron, will change over in 2018, the service said.