America’s new trillion-dollar fighter jet under fire again by Clay Dillow @FortuneMagazine August 14, 2015, 11:58 AM EST E-mail Tweet Facebook Linkedin Share icons It’s tough being the world’s most expensive weapon system. Years behind schedule and billions over-budget, the F-35 Joint Strike Fighter program has had to absorb its fair share of critiques. Over the past several years, it’s been described as too complex, too reliant on high-tech sensors and software, and—at $400 billion for development and procurement—far too costly. A spate of recent program milestones—including being declared operational by the U.S. Marine Corps last month—seemed to suggest the program might be turning a corner this summer. But a scathing report published Monday by a D.C.-based think tank indicates otherwise. To paraphrase analysts at the progressive National Security Network (NSN): The F-35 Lightning II fighter jet will perform horrendously against “near-peer” enemies, and the Department of Defense should rethink its proposed buy of nearly 2,500 F-35s. “The F-35 will find itself outmaneuvered, outgunned, out of range, and visible to enemy sensors,” the NSN report reads. “Going forward, full investment in the F-35 would be to place a bad trillion-dollar bet on the future of airpower based on flawed assumptions and an underperforming aircraft. To avoid such a catastrophic outcome, Congress and DOD should begin the process of considering alternatives to a large-scale commitment to the F-35.” That’s a fairly damning assessment of an aircraft designed to be the workhorse multirole fighter jet for the U.S. and its allies for the next few decades. The Lockheed-Martin-built F-35 is slated to replace a number of jets across the American service branches, including U.S. Air Force F-15s and F-16s, and U.S. Navy and Marine Corps F-18s. Several foreign militiaries have also pledged to purchase the F-35, including Canada, Australia, Japan, and the United Kingdom. The nearly-40-page report details what NSN’s analysts see as the F-35’s major shortcomings: Its internal payload bay is too small to be effective in modern air-to-air engagements; its relatively short operating range will limit its capability in geographically large areas (like the increasingly important Asia-Pacific region), and; it relies too much on stealth technology that will grow increasingly obsolete as air defenses improve over time. The report also piles atop recent criticism that the F-35 is less maneuverable than some of the previous generations it is meant to replace, placing it at a disadvantage in air-to-air combat. In late June, defense blog War is Boring unearthed an unclassified five-page brief written by an F-35 test pilot after simulated air-to-air—or “dogfighting”—trials pitting an F-35 against a 1980s vintage F-16D. That brief described a lopsided competition in which the F-16 consistently outmaneuvered its newer, stealthier counterpart. The F-35 could neither effectively attack its more agile adversary, nor could it escape when the F-16 took to the offensive. Think tanks don’t make policy, and the NSN’s conclusion that the Pentagon should move away from the F-35 might not be all that meaningful in the end. But it’s a sentiment that’s been echoed elsewhere in D.C., and by individuals with access to the chain of decision-making. While members of Congress have largely backed the F-35 (the program has a footprint in 44 states and Puerto Rico), some voices within the military establishment and executive branch have expressed misgivings about the F-35 in recent months. Most notably the incoming chairman of the Joint Chiefs of Staff recently told the Senate that the total F-35 buy is under review. In response to written questions put to him during confirmation hearings for his appointment to the Joint Chiefs, Marine Gen. Joseph Dunford Jr. wrote “given the evolving defense strategy and the latest Defense Planning Guidance, we are presently taking the newest strategic foundation and analyzing whether 2,443 aircraft is the correct number.” Both the F-35 program and Lockheed Martin have been called “too big to fail,” but that doesn’t mean that the program is too big to trim. If the Pentagon were to significantly scale back its F-35 purchase that would be bad news for Lockheed, potentially costing billions in future revenue while driving the cost per aircraft higher still. Partner nations like Italy and Australia have already curtailed their F-35 purchase plans. Reduced orders from its primary customer in Washington, D.C., would undoubtedly hurt. Currently there are no public plans for the Pentagon to move away from the F-35, however loud the calls to do so are. For its part, Lockheed Martin LMT says the aircraft has been largely misunderstood. Hitting back against the earlier criticisms that the next-generation jet couldn’t match a last-generation F-16 in combat maneuvers, Lockheed released a statement saying that the test aircraft used for the demonstration wasn’t carrying the sensor technologies that would obviate the need for the F-35 to engage in a close-range air-to-air battle in the first place. “The F-35’s technology is designed to engage, shoot, and kill its enemy from long distances, not necessarily in visual ‘dogfighting’ situations,” the statement reads. The test aircraft lacked the technologies that “make them virtually invisible to radar,” the statement says, and was “not equipped with the weapons or software that allow the F-35 pilot to turn, aim a weapon with the helmet, and fire at an enemy without having to point the airplane at its target.” But from a political standpoint, whether or not the F-35 is indeed so technologically amazing that it doesn’t need to be able to dogfight may be a moot point, as might the other criticisms put forth in the NSN report. Lockheed already does business with 1,300 contractors and subcontractors across the vast majority of U.S. states, and its pending acquisition of Connecticut-based helicopter manufacturer Sikorsky further extends its presence and influence in a region where previously it had little. All those jobs and all that federal money make it hard for legislators to turn away from the program. Even if the F-35 could potentially be bested in a dogfight, it could prove extremely tough to outmaneuver in Congress. Sign up for Data Sheet, Fortune’s daily newsletter about the business of technology.