Why is the U.S. military anxious? 

The U.S. Air Force and Space Force Magazine claimed that the reason why the Pentagon is eager to advance the development and equipment of the B-21 is to "respond to the Chinese threat."The report mentioned that among the bombers currently in service in the U.S. Air Force, the B-1B has been overused in previous local wars, and its lifespan has expired and is in urgent need of replacement; the B-52 has been in service for decades, has limited performance, and can only be used as a launch platform for off-zone weapons. ; It is difficult to say how effective the B-2 bombers will be when facing China’s advanced air defense systems. Moreover, their number is too small and their maintenance costs are too high.Therefore, the U.S. Air Force urgently needs a new generation of B-21 stealth bombers to maintain air supremacy.However, many types of advanced weapons currently developed by the United States have problems with progress delays, including the B-21, which was originally planned to fly for the first time in December 2021. As a result, the first flight was delayed by two years.These are important reasons why the US military has taken measures to speed up its service.However, some analysts believe that the "test flight and production at the same time" model adopted by the B-21 is likely to be "haste, waste in speed".Previously, the United States strongly praised the effects of digital engineering when developing the F-35 fighter jet, hoping to gradually improve combat capabilities in different production batches with the help of iterative and progressive ideas in software engineering.However, in actual production, due to insufficient testing and immature software and hardware problems, the F-35 development progress was seriously delayed, and grounding accidents continued one after another.It remains to be seen whether the B-21 will follow in the footsteps of the F-35 in its development process.