Well, in a time of actual war, I could see our genetic scientists developing a biological weapon using an altered rhinovirus (common cold virus) and combining it with the Ebola virus and using it on actual enemy troops in the combat area. This nonsense that "we shouldn't use land mines and gas is absurd. The aim is to literally kill the enemy to win.
If we look back at our conflicts since the Geneva Convention, the only nation that really held to it, was the US. Our enemies (aside from Germany occasionally abiding by it), never abided by it, therefore, neither should we. You give wat you get.