The Lockheed Martin F-35 program is a vast undertaking and will eventually see the fighter jets sold to countries all around the world. The question at this time is how many of the aircraft that were originally ordered by the various partner countries will actually be purchased and shipped once the aircraft are operational.

The F-35B STOVL version of the fighter has had some serious issues of late that have prevented testing flights and STOVL operations entirely. The latest snag in the program comes as word that partner country Britain is changing its mind on the purchase of F-35B aircraft and going with the conventional F-35C carrier version of the fighter.

The reason for the U.K.'s move to the F-35C version of the aircraft rather than the STOVL version is that plans for building two new carriers are in flux. As it stands, Britain's carriers are not capable of working with allied French and U.S. naval fighters because the British warships lack the catapult and arresting gear for carrier take off and landings required by allied aircraft.

Not surprisingly, this is unwelcome news to Lockheed Martin. "We will work closely with the U.K.'s Ministry of Defence to assess the impact of any reductions to the program and to support their decision,” said the company in a statement to Defense News.

The first hint that Britain might be having second thoughts on the F-35B came this week when the foreword to a new national security strategy written by Prime Minister David Cameron and Deputy Prime Minister Nick Clegg was published. The foreword complained that the two carriers the Royal Navy were set to construct "… [are] unable to operate with the aircraft of our closest allies."

Britain is looking to make defense spending cutbacks and fitting its new carriers with the catapult and arrestor gear that would allow the ship to work with U.S. and French planes would be cheaper and offer more capability. A Ministry of Defense spokesman said that the change to a conventional carrier would make the new carrier, "cheaper, deliver more capability and go further."

Britain is also considering changing the second of the 65,000-ton carriers to an amphibious helicopter role rather than a standard carrier. The second carrier could also be eliminated altogether. The carrier currently under construction was originally designed for catapult and arrestor gear to be added later if needed. The F-35C has already been purchased by Britain in small numbers for test and evaluation. The U.S. Navy is currently the only confirmed buyer of the F-35C.

Britain was set to make a final decision on buying more of the STOVL fighters next year and had originally planned to buy 150 F-35B fighters – the number was later reduced to 138 and could go even lower. Construction of the first of the new British carriers is underway with the ship set to enter service in 2016.