Basically

what you got.

The film does not go deeply into his motivations.

And quite frankly, his scheme doesn't stand up to any sort of logic.

Because what he does, as you said at the beginning, is hijack two nuclear subs, and he's going to use them to fire nuclear warheads at Moscow and New York City, thereby creating retaliation, nuclear war, and global annihilation.

Somehow ignoring the fact that the seawater does not protect you from radiation.

So if the world is irradiated, that's not going to work out.

And then the place explodes and he's gone.

Basically

what you got.

The film does not go deeply into his motivations.

And quite frankly, his scheme doesn't stand up to any sort of logic.

Because what he does, as you said at the beginning, is hijack two nuclear subs, and he's going to use them to fire nuclear warheads at Moscow and New York City, thereby creating retaliation, nuclear war, and global annihilation.

Somehow ignoring the fact that the seawater does not protect you from radiation.

So if the world is irradiated, that's not going to work out.

And then the place explodes and he's gone.