I wanted to first address the question of being overridden. When you enter into any sort of relationship - dating, marriage, inhabiting a city, living in a country - you are agreeing to compromises to grease the wheels of society. Some people are always going to lose sometime - ideally those aren't always the same people and nobody loses an excessively burdensome amount but... If you live in a city of three million you probably fervently disagree with a few hundred thousand of the other residents on some issues you consider particularly important.
On the topic of actions considered immoral (or I'll start with illegal) when done by an individual - war actually only fits into this category in some countries, in a lot of areas murder in self-defense is legal and if 100 ninjas tried to murder you and it was clearly a case of self defense where all other actions were barred your actions might be legal in the US - they would probably be universally recognized as moral by everyone except the most staunch utilitarians which I assume would respond: "Dude - take the trolley in the face, duh - even if they started it it's 100 vs 1 lives lost".
That all said, war is frequently not a case of self-defense and is often abused for silly things like resource acquisition and prestige. Better representation allows us to severely punish governments that either look like they're going to go against the societal will or remove them after the fact - buuut there will be times when a country goes into unpopular wars justly due to either domestic misinformation or classification of information creating a different breadth of knowledge between law makers and the populace - with the former seeming more likely and the latter being pretty repulsive. And the freedom to act in response to aggression is one we need to keep separated from the slow response time of something like a pure democracy. This was actually the case in Athens where Strategos were free to act during their term (assuming an agreement between the then Strategoi) and were only subject to removal during regularly scheduled sessions.
I am strongly against war myself but I would be pretty happy with the US entering and occupying posts in civilian areas on both sides of the israeli/palestinian border to dissuade both parties from continuing attacks - I'm similarly okay with cypric occupation since that situation seems similarly unresolvable. War is pretty complicated but I don't think it's all that distinct from other issues a nation needs to deal with, poor representation leads to actions that go against the public will.