The cost of the F-35 Joint Strike Fighter rose to $395.7 billion last year as the most expensive program in the Pentagon’s history continues to struggle with cost overruns and delays.

The Pentagon recently submitted to Congress its Selected Acquisition Report (SAR) that outlined new data on the program’s performance and anticipated costs. The Pentagon attributed the increase to inflation, a slowed production ramp rate and fewer international sales.

The revised figure assumes the Pentagon will stick with plans to buy 2,443 of the Lockheed Martin [LMT]-built aircraft under the three variants for the Air Force, Navy and Marine Corps.

Additionally, a Pentagon official confirmed the total cost of procuring and operating the entire fleet of F-35s over the next 50 years will approach $1.5 trillion. That includes operations, maintenance and fuel costs.

Meanwhile, acting Pentagon acquisition chief Frank Kendall approved continued low-rate initial production of the aircraft. The F-35 is heading toward its fifth round of low-rate production. The fighter program has been plagued with costs overruns caused by having to engage in redesign to resolve problems discovered in developmental testing.

The problems have prompted he Pentagon to curtail production by delaying construction on 179 of the planes planned for over the next five years, a move estimated to save $15.1 billion.