Even if you don't imagine robots becoming self aware and deciding to kill humans on their own, you can imagine a fleet of drones and self-driving tanks controlled by a deep learning network. They don't need to understand what they're doing to make effective tactical decisions.

If the US doesn't do this, someone else probably will.

We're going to see an AI-based blitzkrieg attack in our lifetimes.

Once you can launch an invasion without losing any soldiers, war seems like a much less dangerous proposition.