This reminds me a bit of Macchiavelli. Of course I haven't read Macchiavelli, but it seems to me that he wants to achieve his goals optimally, even if it means making decisions that are immoral in the eyes of the public. A bit favoring the end over the means, like in the trolley problem, when you are killing people in war to prevent a greater evil. Goal-based over principle-based ethics.

In terms of strategy, you could look at game theory. The prisoner's dilemma is about waging cooperation against betrayal or competition. Peace might be better for both countries, but if you are in a war, it's better when you do the first strike. It's still possible for cooperation to be strategically better, for example when you build up a trustworthy reputation over time in the "repeated prisoners dilemma".

Some countries are torn by corruption or civil wars. That might be just because they haven't had a chance to build a trustworthy reputation with each other.

The "Golden Rule" or Kant's similar categorical imperative say that you shouldn't do to others, what you don't want them to do to you. That would mean that you shouldn't start wars. I think this doesn't work then the other party is either evil or irrational or weak. You wouldn't want your kid to send you to bed at seven o'clock, but you can still do that to your kid. You can also imprison an insane murderer.

If you threaten violence, you might be able to control more people than if you actually exert violence. If you have one nuclear bomb you can hit destroy one enemy country but you can threaten to destroy multiple countries.

Practically speaking, in international politics you also have to consider the opinions of every other state. When you are an aggressor, they might ally against you. International law works similar to national law. Abiding to laws is often advantageus. Thomas Hobbes said something about that without laws, humans are wolves. But we have international laws or at least conventions, so states shouldn't be wolves either.

On a battlefield it is of course sometimes better to be defensive. I think Sun Tsu said, that you should only engage an enemy army, when you are stronger (like twice the number of soldiers or something). When you are behind a wall or on a hill, you don't leave your advantageus position. A chess move that takes a piece is not always better than one that doesn't. This is probably not what you meant, is it? "Always take the more aggressive tactical option!"