F-15EX fighter jet. According to foreign media reports, the US Government Accountability Bureau recently released the latest progress report on the F-15EX fighter jet. It is expected that the delivery of six F-15EX fighter jets will be delayed by at least six months, which will directly affect the formation of the initial combat effectiveness of the fighter jet and the large-scale production of subsequent models. The already controversial F-15EX fighter jet has once again become the focus of public opinion. The F-15EX fighter jet is the latest upgraded model based on the F-15QA fighter jet, equipped with a digital cockpit, open mission system, and active warning system. The aircraft does not have stealth capability, with a maximum payload of 13 tons. It is said to be capable of carrying 22 AIM-9X "Rattlesnake" missiles, and can provide strong Fire support when fighting with F-22 and F-35 fighters. Multiple reasons have delayed the delivery of the first F-15EX fighter prototype for testing by the US Air Force in March 2021. In April of the same year, the second prototype was delivered nearly 8 months ahead of the contract time. Despite the good development momentum in the early stage, two years have passed, and currently the US Air Force only has two aircraft received in the initial stage. In response, foreign media analyzed the reasons why the remaining six aircraft were not delivered as planned by the end of 2022, based on a report from the US Government Accountability Bureau. Quality issues delay production progress. The report clearly points out that there are potential issues with the key components of the front fuselage of the F-15EX fighter jet, which have affected flight safety. Although Boeing has resolved the related issues during the manufacturing of the 7th and 8th fighter jets, time is still needed to repair the remaining four key components. In addition, the report points out that Boeing used incorrect drilling tools during the production process, resulting in inaccurate drilling of the windshield installation of the 3rd to 6th fighter jets, affecting assembly progress. The variability of procurement plans affects production plans. The report points out that the US Department of Defense bears significant responsibility for production delays. At first, the US Department of Defense should finalize the final purchase quantity of F-15EX fighter planes in September 2021, so that the manufacturer could arrange the production schedule. However, it delayed for six months, and did not formally finalize the total purchase quantity until the release of the Military budget for fiscal year 2023 in March 2022, and reduced the total purchase quantity from 144 to 80, and then to 78 in June of the same year. In March of this year, when the US Department of Defense released the Military budget for fiscal year 2024, the total number was increased to 104. Frequent changes in procurement plans have caused significant interference for Boeing in selecting component suppliers and arranging production lines, affecting the overall project schedule. Complex factors affect the production process. The report points out that there are disagreements between the Defense Contract Management Agency under the US Department of Defense and Boeing regarding the "business management system", which has affected early production planning. In addition, uncertainties such as the COVID-19 also led to several interruptions in production. The follow-up will trigger a chain reaction. Several US media outlets have expressed strong concerns about the delayed delivery of F-15EX fighter jets, believing that this move will trigger a negative chain reaction. Firstly, the stability and reliability of the F-15EX fighter jet are being questioned