Historically the US has favored protectionism over subsidies, but my understanding is that subsidies are almost always a more economically optimal way of ensuring that strategically-important domestic industries are able to survive.
Eternally subsidizing massive shipbuilding infrastructure as an insurance policy against WW3 seems beyond silly in my view. And remember, it has to be massive shipbuilding infrastructure or you're not doing any good. Having one or two shipyards that aren't very good at shipbuilding does zero if you need to suddenly build a lot of ships locally for "national security" which seems to be the argument of the pro-jones act commenters.
