F-35 Joint Strike Fighter (JSF) Program: Issues for Congress
(Source: Congressional Research Service; issued May 14, 2020)
(This report includes the longest and most detailed list of “Issues for Congress” that the Congressional Research Service has ever published on the F-35 Joint Strike Fighter program. It also uses language that is more straightforward than generally used by CRS and, finally, explores in detail a number of historical factors that are key to understanding the program’s current status – Ed.)

Overall Need for F-35

The F-35’s cutting-edge capabilities are accompanied by significant costs. Some analysts have suggested that upgrading existing aircraft might offer sufficient capability at a lower cost, and that such an approach makes more sense in a budget-constrained environment. Others have produced or endorsed studies proposing a mix of F-35s and upgraded older platforms; yet others have called for terminating the F-35 program entirely. Congress has considered the requirement for F-35s on many occasions and has held hearings, revised funding, and added oversight language to defense bills.

As the arguments for and against the F-35 change, the program matures, and/or the budgetary situation changes, Congress may wish to consider the value of possible alternatives, keeping in mind the program progress thus far, funds expended, evolving world air environment, and the value of potential capabilities unique to the F-35.

Planned Total Procurement Quantities

A potential issue for Congress concerns the total number of F-35s to be procured. As mentioned above, planned production totals for the various versions of the F-35 were left unchanged by a number of reviews. Since then, considerable new information has appeared regarding cost growth and budget constraints that may challenge the ability to maintain the expected procurement quantities. “’I think we are to the point in our budgetary situation where, if there is unanticipated cost growth, we will have to accommodate it by reducing the buy,’ said Undersecretary of Defense Robert Hale, then Pentagon comptroller.”155

Some observers, noting potential limits on future U.S. defense budgets, potential changes in adversary capabilities, and competing defense-spending priorities, have suggested reducing planned total procurement quantities for the F-35. A September 2009 report on future Air Force strategy, force structure, and procurement by the Center for Strategic and Budgetary Assessments, for example, states that

[A]t some point over the next two decades, short-range, non-stealthy strike aircraft will likely have lost any meaningful deterrent and operational value as anti-access/area denial systems proliferate. They will also face major limitations in both irregular warfare and operations against nuclear-armed regional adversaries due to the increasing threat to forward air bases and the proliferation of modern air defenses. At the same time, such systems will remain over-designed – and far too expensive to operate – for low-end threats....

Reducing the Air Force plan to buy 1,763 F-35As through 2034 by just over half, to 858 F-35As, and increasing the [annual F-35A] procurement rate to end [F-35A procurement] in 2020 would be a prudent alternative. This would provide 540 combat-coded F-35As on the ramp, or thirty squadrons of F-35s[,] by 2021[, which would be] in time to allow the Air Force budget to absorb other program ramp ups[,] like NGB [the next-generation bomber, B-21].156

Block 4/C2D2 as a Separate Program

Development of the F-35 Block 4 software, part of an effort now called Continuous Capability Development and Delivery (C2D2), is expected to cost as much as $10.8 billion over the next six years.157 “The F-35 Joint Program Office (JPO) plans to transition into the next phase of development – Continuous Capability Development and Delivery (C2D2) – beginning in CY18, to address deficiencies identified in Block 3F development and to incrementally provide planned Block 4 capabilities.”158

“The JPO’s latest plan for F-35 follow-on modernization ... C2D2, relies heavily on agile software development—smaller, incremental updates to the F-35’s software and hardware instead of one big drop, with the goal of speeding follow-on upgrades while still fixing remaining deficiencies in the Block 3F software load.”159

Some in Congress argue that a program of that size should part with traditional procurement practice for an upgrade and be run as a separate Major Defense Acquisition Program (MDAP), with its own budget line and the concomitant requirements. At a March 23, 2016, hearing of a House Armed Services subcommittee,

Government Accountability Office (GAO) Director of Acquisition and Sourcing Management Michael Sullivan argued that the Block 4 estimated cost justifies its management as a separate program, but F-35 Program Executive Officer (PEO) Air Force Lt. Gen. Christopher Bogdan countered that breaking it off would create an administrative burden and add to the program’s price tag and schedule.160

The House-passed version of the FY2020 National Defense Authorization Act (H.R. 2500) contained a provision (§132) that would require the Secretary of Defense to designate the C2D2 program as a major subprogram of the F-35 program. As enacted into law, the act (P.L. 116-92) does not designate Block 4 and/or C2D2 as a major subprogram, but requires the Secretary of Defense to submit an annual integrated master schedule and past performance assessment for each planned phase of Block 4 and C2D2 upgrades.

An emerging issue is the continued oversight of Block 4. As GAO noted in May 2020, delays in the program mean that the Block 4 effort is now likely to last longer than its congressional reporting requirement. 161 The National Defense Authorization Act of 2017(P.L. 114-328) included language requiring annual reports on the progress of Block 4 through 2023. As the program is now projected to continue through 2026, Congress may wish to consider extending that requirement or other oversight measures.


Lieutenant General Bogdan’s comments regarding the difficulty of cost control in a sole-source environment (see “Engine Costs,” above) reflect a broader issue affecting defense programs as industry consolidates and fewer sources of supply are available for advanced systems. Congress may wish to consider the merits of maintaining competition when overseeing system procurements (for example, the use of competition to maintain cost pressure was a principal argument in favor of the F-35 alternate engine program).162 On the F-35 program, that competition could include contracting for lifecycle support as a way to address sustainment costs.

Appropriate Fighter Mix

A significant issue, beginning with the FY2020 DOD budget submission, is the optimal mix of fighter aircraft in the Air Force fleet. Previous plans had focused on the F-35 as the mainstay of the future fighter fleet, in keeping with an Air Force initiative to move to an all-fifth-generation-and-beyond force. In FY2020, however, the Air Force requested an initial 8 of a projected buy of 144 F-15EX fighters. The F-15EX is an improved version of the F-15 Eagle and Strike Eagle fighter series, which the U.S. last acquired in 2001.163

Subsequently, the Air Force justified the request on two grounds: that the operating costs of the F-35 were significantly higher than fourth-generation aircraft like the F-15EX, and that the service needed to acquire 72 new fighters per year to maintain its fleets as older aircraft retire.164

The Air Force has maintained that F-35 and F-15EX do not compete directly for funding. Observers note that, regardless, the F-15EX proposal came at a time when the Air Force reduced its planned F-35 buy from 60 to 48 jets per year. Further, some argue that the additional capabilities inherent in the F-35 provide a better value at similar cost.165 F-15 advocates note the age of current U.S. F-15s, and that new F-15EXs offer better value than extending the lives of existing ones.166

More recently, the Air Force has been considering replacing some F-16s, which had been expected to be replaced by F-35s, with unmanned systems instead. [Air Combat Command commander Gen. Mike] Holmes suggested that low-cost and attritable unmanned aircraft systems (UAS) might be considered… as a replacement for F-16 Block 25/30 jets… within 5-8 years. In congressional testimony on March 12, Holmes added that ACC’s goal is to achieve a fighter fleet ratio of 60% fifth-generation jets, such as F-35As and F-22s, to 40% fourth-generation aircraft, including F-15s, F-16s and A-10s. 167
That ratio had previously been expressed as 50-50.168

Engine Cost Transparency

In the specific case of the F-35, Pratt & Whitney and the Joint Program Office have declined to reveal the cost per engine in each LRIP contract, replacing dollar costs with percentage savings and aggregate contract values that include items other than the engines themselves. Congress may wish to consider whether this approach is sufficient to provide useful oversight, and weigh that value against a contractor’s right to protect competition-sensitive data. A possible analogue can be found in the debate over whether public disclosure of the contract value for the B-21 bomber might reveal more data than prudent, or whether that is a reasonable cost to allow proper program oversight.


An additional potential issue for Congress for the F-35 program concerns the affordability of the F-35, particularly in the context of projected shortfalls in both Air Force fighters and Navy and Marine Corps strike fighters.

Although the F-35 was conceived as a relatively affordable strike fighter, some observers are concerned that in a situation of constrained DOD resources, F-35s might not be affordable in the annual quantities planned by DOD, at least not without reducing funding for other DOD programs. As the annual production rate of the F-35 increases, the program will require more than $10 billion per year in acquisition funding at the same time that DOD will face other budgetary challenges.

The issue of F-35 affordability is part of a larger and long-standing issue concerning the overall affordability of DOD’s tactical aircraft modernization effort, which also includes procurement of F/A-18E/Fs, increasingly capable unmanned aerial vehicles, and, as mentioned, F-15EXs.169

Implications for Industrial Base

Another potential issue for Congress regarding the F-35 program concerns its potential impact on the U.S. tactical aircraft industrial base. The award of the F-35 SDD contract to a single company (Lockheed Martin) raised concerns in Congress and elsewhere that excluding Boeing from this program would reduce that company’s ability to continue designing and manufacturing fighter aircraft.170

Similar concerns regarding engine-making firms have been raised since 2006, when DOD first proposed (as part of the FY2007 budget submission) terminating the F136 alternate engine program. Some observers are concerned that if the F136 were cancelled, General Electric would not have enough business designing and manufacturing fighter jet engines to continue competing in the future with Pratt & Whitney (the manufacturer of the F135 engine). Others argued that General Electric’s considerable business in both commercial and military engines was sufficient to sustain General Electric’s ability to produce this class of engine in the future.

Exports of the F-35 could also have a strong impact on the U.S. tactical aircraft industrial base through export. Most observers believe that the F-35 could potentially dominate the combat aircraft export market, much as the F-16 has. Like the F-16, the F-35 appears to be attractive because of its relatively low cost, flexible design, and promise of high performance. Competing fighters and strike fighters, including France’s Rafale, Sweden’s JAS Gripen, and the Eurofighter Typhoon, are positioned to challenge the F-35 in the fighter export market.

Some observers are concerned that by allowing foreign companies to participate in the F-35 program, DOD may be inadvertently opening up U.S. markets to foreign competitors who enjoy direct government subsidies. A May 2004 GAO report found that the F-35 program could “significantly impact” the U.S. and global industrial base.171 GAO found that two laws designed to protect segments of the U.S. defense industry—the Buy American Act and the Preference for Domestic Specialty Metals clause—would have no impact on decisions regarding which foreign companies would participate in the F-35 program, because DOD has decided that foreign companies that participate in the F-35 program, and which have signed reciprocal procurement agreements with DOD to promote defense cooperation, are eligible for a waiver.

Future Joint Fighter Programs

Congress consolidated the JAST and ASTOVL programs after finding “no apparent willingness or commitment by the Department to examine future needs from a joint, affordable, and integrated warfighting perspective.”172 DOD states that the F-35 program “was structured from the beginning to be a model of acquisition reform, with an emphasis on jointness, technology maturation and concept demonstrations, and early cost and performance trades integral to the weapon system requirements definition process.”173

A subsequent RAND Corporation study found that the fundamental concept behind the F-35 program—that of making one basic airframe serve multiple services’ requirements—may have been flawed.174

Congress may wish to consider how the advantages and/or disadvantages of joint programs may have changed as a consequence of evolutions in warfighting technology, doctrine, and tactics.

Click here for the full report (45 PDF pages), on the CRS website.


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