There are a number of transhumanist aspects that could make war less problematic:
- Confine the war to a realistic virtual/augmented reality setting. Something like the following might be a precursor to that: https://www.indiegogo.com/projects/father-io-massive-multiplayer-laser-tag-app#/
- Wage war with robots and drones only, ideally against armies that also only use robots and drones. Spare civilians.
- Make backups of soldiers before they are sent into battle and revive them as uploads if they happen to die.
Would those aspects make war look more desirable? Probably yes, since they would decrease the associated risks and costs of wars. The problem though, is that war is something that is hard to confine to “cleaner” approaches. It’s still possible, and to some degree plausible, since nuclear, biological, and chemical weapons have been used very rarely after humanity has found our just how devastating and dangerous they are.
Still, wars come at a high economic cost, and should only be used as a means of last resort. Could starting wars be justified when they are supposed to stop things that are even worse? Possibly, but usually wars don’t make situations better, but worse, so wars generally are a really bad idea.
The usual transhuman approach is: Throw science, technology, and resources onto the problem until it’s fixed. That usually works, if you try hard and persistently enough.
Intelligent information weapons: Cyber warfare, nanobots, exploiting the weaknesses of the information processing systems of your enemies. This approach minimizes collateral damage, if it’s done right.
Cloaking devices: You can hardly defeat what you cannot see.
Increasingly, war is replaced by economic and political competition. That’s usually preferable to war, until it reaches extreme heights, at which point violent resistance against overwhelming oppression starts looking like the most reasonable option. In other words: The forms of structural violence that have mostly replaced outright wars are the main factors that can drive future wars. War is always only the tip of the iceberg. We need to go deeper!