And another reasons is that dollar is a world-wide reserves currency. This arrangement essentially creates unlimited credit for US. To maintain this status carriers, planes and other weapons are required.
While everyone in US benefits from this, (mostly) liberals disingenuously “protest”. You know, if you really care about this issue, then blue-collar protection policies, like some recent president tried, would go a long way to lift lower middle class and paradoxically reduce a need to project force world-wide all the time.
That's another side to projects like the F-35 that people on HN usually don't pay attention to. This programs not only "create" those jobs but they also keep the infrastructure and "machine" running that can design and build this very powerful weapons. The US had air superiority because of its technology for a while and if all that infrastructure and people just start doing something else, in like 5/10 years then the capacity to build this machines is dead, and it would take 10/15 years to get it back up and running.