Also.
As a regular role-player, I can say this kind of game is silly for this kind of problem. It all depends on the starting assumptions of the roles people are playing. If you're choosing to roleplay someone more interested in their national power, than you'll play that character. If you choose to play a character who doesn't care about personal advantage, you'll play that way.

In addition, the GM can create the incentives by choosing the specific form and controls of the technology, and political landscape.

The term War-Game itself, predisposes the game to be adversarial in nature. Surprise surprise, that's how it played out.