Because they are demanding that Lockheed Martin, rather than the tax payers, will have to cover at least some of the costs: (Paid sucscription required)

Prolonged delays in development of the F-35 Joint Strike Fighter are coming home to roost for Lockheed Martin, as the Defense Department moves to force the manufacturer to bear the cost of any changes to production aircraft that could result from the thousands of hours of flight testing that still lie ahead.

Even as development has fallen behind schedule, Lockheed has continued to produce aircraft and the resulting overlap, or concurrency, has driven up the cost of the initial batches of F-35s, forcing the cutback on procurement to cover the overruns.

Crying foul 10 years after his company signed the F-35 development contract, CEO Bob Stevens revealed last month that the government has failed to reimburse Lockheed Martin for up to $1.2 billion in costs associated with low-rate initial production (LRIP) Lot 5. And those bills may not be paid until the company agrees to negotiate what Stevens says is an “unprecedented” contract provision, called a concurrency clause, for the next production lot of aircraft.

Such a clause would place the burden of financial liability on the contractor team for design changes to the LRIP 5 jets that result from discoveries made during the ongoing flight-test program. Stevens declined to outline how much liability the government is intending to place on the contractors.

…………

But while progress is being made, an October memo signed by the Pentagon’s chief tester has added to cost anxieties, indicating it could require an additional 10 months to begin F-35 pilot training, which was expected to start in the fall. It is now more likely to begin next spring, at the earliest. Further delays in pilot training could increase costs for customers who will be required to operate older fleets for a longer time until F-35s can be accepted into service. The memo adds to concerns that testing on the aircraft is too immature to proceed with pilot training and operational use.

(emphasis mine)

The problem is that the Pentagon wants the contractor to cover the costs of the post production modifications required for the early-build airframes as a result of delays in the test program.

This is an indication of desperation on the part of the Pentagon, because this jeopardizes the general’s lucrative post-retirement employment with the defense contractors.

This means that the program is in enough jeopardy that DoD feels the need to get tough with their future employers, which is kicking out a leg of the Iron Triangle.

I’m beginning to think that we won’t procure any more of these than we did the F-22.