Eliminating wars by designing and deploying a highly contagious brain virus to change human nature for the better
Is such a thing feasible? Would you classify it as terrorism?
Of course not! It's just not even remotely feasible. There are two reasons, but I'll start with the big one.
We have shown a marked inability to micromanage "changing human nature for the better." We just don't understand enough about the brain to make e.g. violent criminals stop being violent, using psychology, drugs, surgery, or anything else really. See any crime statistics you like on the subject. The one exception is wherein we can stop someone from being violent, by basically stopping them from doing anything -- not a desirable outcome as applied to the entire human population.
The second reason it's not feasible is, well... What happens to the one guy who finds out about this, and spends a year in his basement becoming completely immune to the vector? People are resistant to gene therapy vectors from time to time, with no deliberate action. Deliberate action just makes this scenario more likely.
Eliminating violence is a nice sentiment, but this methodology is just not even remotely feasible. Ethics are a whole other can of worms.
Among other novel uses of tech in warfare, they deploy an 'empathogenic' aerosol which goes to work on the empathy centers of the brain, making people permanently unable to kill. The story revolves around an American soldier who was accidentally exposed to it. See: http://www.e-sheep.com/spiders/3.5/10_knife.html and http://www.e-sheep.com/spiders/3.5/000_hospital.html and http://www.e-sheep.com/spiders/3.5/11_epilogue.html
So what would happen if war is never an option?
Often, but not always. The security dilemma is another major cause of wars.
No, rarely. The Second World War was party about resources, in that Hitler wanted lebensraum, and the proximal cause for the USA getting into the war was Imperial Japan's desire for the oil and territory of the Dutch East Indies. But Japan only wanted to take that because its wars of conquest got it embargoed. Had it stayed peaceful it could have just bought the oil, a much cheaper prospect. So, it's more like the oil was an issue because of the war, not the need for oil causing the war. However, Vietnam, Korea, WWI, the American civil war, and the war for independence... what resouces are you talking about?