Take the submarine as an example. The submarine itself can't apply for a patent, but if it is original, it can apply for a patent for an oxygen generating device, a damping raft and a silencing tile.
Russia often claims that China has infringed its weapon patent right, but this right has no legal basis. It just used the word patent to remind China to stop copying its weapon system. If China ignores him and doesn't sell at most in the future, he won't win the lawsuit.