The Marine Corps has received its first two F-35Bs for its fighter training squadron at Eglin AFB, Fla.

The 33rd Fighter Wing, Marine Fighter Attack Training Squadron 501, took the Marine Corps version of the Joint Strike Fighter (JSF). The F-35Bs feature a short take-off and vertical landing (STOVL) capability.

The training squadron now has eight JSFs, including the F-35A variant used by the Air Force. Five more Lockheed Martin [LMT]-built F-35Bs are expected to arrive later this year. The planes will be used for pilot and maintenance training, the Marines said.

The Air Force, Navy and Marine Corps combined are buying more than 2,500 of the advanced multirole fighter, for an estimated price tag of about $383 billion, making it the most expensive acquisition program in the Pentagon’s history.

The JSF program has been plagued by massive cost overruns and lengthy delays, prompting sharp criticism and some members of Congress to call for its cancellation.

The Marine Corps variant has been the most troubled, and was put on two-year probation about a year ago. The challenges with the variant have been the most difficult to overcome because of the STOVL feature.

Lt. Gen. Terry Robling, the Marines’ aviation chief, said in September that he did not expect the F-35B to reach initial operational capability (IOC) until 2015. He expressed confidence, however, that the program will be able to come off of probation on time, and that most of the major problems had been resolved.