For example, in Iraq, Saddam was able to use chemical weapons and wipe out the resistance, this is no longer an accepted solution by majority of people on earth.

So there is no real way to actually win a war. If you can't kill or enslave the other population, and the world is not accepting refugees, if you hit one economy completely you might the global economy. So what do you do? there is actually no real way to win a war as those constraints become strong and stronger. You are left with the only option of nulling the other's economy down and hope they would resign, by better co-ordinating your drones and managing your economy, which is a video game in the real world.