The entire idea of carrier naval supremacy is stupid, though. If you look at modern SM-6s, these can hit naval targets up to 500 km away, and cripple them as well due to their hiypersonic speeds. Moreover, the SM-6 can intercept AShBMs as well as threaten aircraft up to 400 km distant. Unless you're planning to load a DF-26 on a J-21, there's little point to set up J-21s. For that matter, DF-21s weigh 15 tons, so they'll easily exceed the load limit of J-21s.