XML Question - How to disable Naval attack to City?

[king_dean]

1. How would you disable a ship's ability to attack a city?
2. How would you disable a city's ability to attack a ship?

 

[king_dean]

In GlobalDefines I was able to turn off the city's ability to attack.
As for disabling the ship's attack ability, all I could do is reduce it's attack strength to zero vs cities, but not technically prevent it.