Until the Russian invasion of Ukraine, there was little evidence of what a conventional war between the regular forces of peer competitors might look like today. After the total war of the twentieth century, the evolution of precision-guided munitions and drones set up the possibility of a new ideal type of conflict, in which U.S.-NATO coalitions could quickly defeat the regular forces of much weaker opponents, largely from a distance, while avoiding excess loss of civilian life. “Smart” weapons created the perception that when civilians were killed, this was an operational failure. Russia's approach to war, however, has not put a high priority on avoiding civilian casualties, but has shown that precise weapons could be used deliberately to target civilian infrastructure in ruthless and coercive air campaigns. In this essay, I suggest that the Russia-Ukraine War provides insight into what a major power war would look like. I contrast the two distinct approaches represented by Ukraine, strengthened by NATO weapons and informed by its concepts, and Russia, with its readiness to attack civil society. I focus on the resulting humanitarian disaster in Ukraine, where more than one-quarter of the population has been displaced and where Ukrainians in Russian-occupied territories have reported thousands of instances of war crimes. I conclude by considering the likelihood and potential consequences of Russia's use of nuclear weapons.