@puzzledperson,
P.S. Ground warfare can also be violently indiscriminate, particularly in a day where stand-off weaponry and indirect fire, such as artillery and infantry air support, are used in urban settings. When armies meet on a battlefield, it's a lot easier to determine "legitimate targets", even though those targets might theoretically be misled youths trying to avoid jail or a firing squad or public shame as a deserter.
Still, if you're aiming a rifle at an individual combatant, there is a restricted intent to your action, and very possibly a restricted effect, that isn't as easy to match by bombing unless your targets are conventional forces on a battlefield.
If you recognize all this, you might be more likely to seek out alternative solutions to war, whether that entails diplomacy, economic sanctions or isolation, or the carrot instead of the stick. Or perhaps, early and limited military intervention, including assassination of those who explicitly beat the drum of aggressive warfare. If the military terms of Versailles had been enforced, despite the supposedly "humiliating" nature of them, perhaps a spot of bother could have been avoided. Of course, the United States never ratified the Versailles Treaty. And guess who sold imperial Japan most of their oil in the lead-up until the rather late date of July 26, 1941?
http://www.history.com/this-day-in-history/united-states-freezes-japanese-assets