An agency of the U.S. Department of Defense is warning the F-35 Joint Strike Fighter is being rushed into service, citing a list of problems with the aircraft.

In a memo recently released by the Defense Department's Operational Test and Evaluation director Michael Gilmore, the agency lists a host of problems with the aircraft including several software complications and even a dangerous ejection process.

Problems with the F-35's ejection seat were identified in October, where testers discovered ejections performed during low-speed flights ran the risk of snapping a pilot's neck.

"The program did not consider this failure to be solely caused by the heavier Gen III helmet, primarily due to similarly poor test results observed with the Gen II helmet on a 103-pound manikin in 2010 tests," the report said.

The F-35 program involves a block buy plan for procurement for U.S. Armed Forces and partner nations participating in the program. The agency's memo says it is possible commitments to a block buy for the aircraft could be made before operational testing is complete.

"The program continues to struggle with Block 3F developmental testing, and in December 2015 the Air Force rated its proposed initial operational capability supported by Block 3i as "red" due to the problems ongoing testing has revealed," the report added.

Numerous software bugs were found, including the aircraft's systems not being able to recognize old parts from new ones, and blocking users from being able to log in to the aircraft's logistics information system.

The F-35 Joint Strike Fighter program is the most expensive military program to date. The U.S. Air Force is scheduled to announce their variant of the multirole fighter is fit to fly between August and December. The Marine Corps declared initial operating capability for their F-35 fleet in 2015.

On Wednesday, Defense News reported the Air Force cut its planned F-35 buy from 48 aircraft to 43. The Air Force F-35 variant is scheduled to reach initial operating capability in August.

The initial operational test & evaluation phase, scheduled for 2017, is "unrealistic" according to the memo, and should be pushed back to "no earlier than August 2018."