Once these get advanced enough and the human cost of starting a conflict goes to zero (because they most likely will be able to scale these to whatever kind of conflict is wanted) why wouldn't countries be more likely to start a war.
Or if most regular military battles only become an economic problem then why wouldn't an enemy turn towards more terrorist like attacks like happened in Russia with ISIS.
America’s second-highest ranking military officer, Gen. Paul Selva, advocated Tuesday for “keeping the ethical rules of war in place lest we unleash on humanity a set of robots that we don’t know how to control.”