Saying "humans have spied on each other for centuries" is nothing but a distraction for how far beyond what should be legal mass surveillance is, because it makes it so easy to have everything on everyone all the time. It's nothing like pass targeted surveillance. If anything it's much more like Stasi-style surveillance, but on a much bigger and more indepth scale. And we already know how dangerous such surveillance is with the wrong person leading a country.
When war becomes easy and cheap (to the attacker), you'll just end up having more of it. It doesn't help the the military industrial complex constantly lobbies for it either.
http://www.wsj.com/articles/SB100014240531119041067045765832...
As far as predicting the future goes, I can't.
Killing people when neither they nor their friends can retaliate is easier. Being able to say do X or I kill you, without the other party having a defense that will even inconvenience you gives you a shitton of power.
Military AI would basically be nukes without the fall-out or collateral damage.
Some people find that scary, and it may seem like a shaky thing to stake your life on. But, firstly, you have no choice. Secondly, it works for billions of people and has kept us safe for tens of thousands of years. Even after we developed the knowledge, tools, and ability to kill millions at the push of a button.
AI doesn't change this it just makes it easier.
The only thing which keeps you alive is the unwillingness of your neighbors and those who surround you to kill you. The law might punish them afterward, but extensive research has shown that it provides no disuasion to people who are actually willing to kill someone.
A military AI being used to wipe out large numbers of people is exactly as 'inevitable' as the weapons we already have being used to wipe out large numbers of people. The exact same people will be making the decisions and setting the goals. In that scenario, the AI is nothing but a fancy new gun, and I don't see any reason to think it would be used differently in most cases. With drones we have seen the CIA, a civilian intelligence agency, waging war on other nations without any legal basis, but that's primarily a political issue and the fact that it can be done in pure cowardice, without risking the life of those pulling the trigger, which I think is a distinct problem from AI.