The timeline for launching the long-troubled F-35 Joint Strike Fighter just moved to the right. Again.

The program, already years behind schedule, won’t be ready for operational testing until mid-2018, a year later than expected, Michael Gilmore, the Pentagon's chief weapons tester, told a House Armed Services Committee subpanel on Wednesday.

Related: Why the F-35 May Not Be Combat-Ready Until 2022

The delay is due to a variety of issues, including the jet’s vulnerability to cyber-attacks and a problem with the fifth-generation fighter’s radar software that caused the system to restart once every four hours of flight time.

“We need the system to be much more stable than that,” according to Gilmore, adding that a reboot once every eight to ten hours would be better.

Air Force Lt. Gen. Christopher Bogdan, the F-35’s program chief, noted “it is not unusual” for legacy aircraft or newer warplanes “every now and then” to reset systems, or have an automatic reset, within that length of time. “That is not an uncommon situation,” the three-star said.

The U.S. Marine Corps declared last July that its version of the F-35 had an initial operational capability and the Air Force plans its F-35 debut by December. However, Gilmore’s testimony clearly indicates that the jet, which has cost nearly $400 billion to develop, would prove of little use if thrown into combat.

Related: More Bad News for the Snakebit F-35

The new snag means that the results of the combat testing, which could take about a year to complete and months more to analyze properly, might not be available until 2020, according to Gilmore’s math.

It isn’t all gloom and despair – again – for the F-35. The aircraft is now projected to cost the Defense Department $379 billion or $12.1 billion less than the $391.1 billion forecast last year, according to written testimony by Michael Sullivan, a senior official with U.S. Government Accountability Office.

The reasons for the new estimate will be disclosed on Thursday as part of the Defense Department’s annual roll out of so-called Selected Acquisition Reports.

Related: Another F-35 Glitch Requires Restarting the Radar System – in Flight

The new price tag isn’t exactly a clear-cut reason for celebration, Sullivan warned.

The F-35 “still poses significant affordability challenges for the department and the Congress,” he said, adding the department is expected to spend about $14 billion annually on the effort over the next decade and will average about $13 billion per year over the next 22 years until all planned purchases are complete in 2038.

“These annual funding challenges will compound as the program begins to stack its funding needs against other large acquisitions, such as the Bomber Program, the Tanker Program that is ongoing, the Ohio Class Submarine Replacement -- the new carrier, and many other very large programs,” according to Sullivan.