We staged a pre-emptive attack on a foreign, sovereign nation.
Our main goal was to apply a regime change in a country that was of no forseeable harm to us whatsoever. Why did the American people support it? Because we were presented false information by our leaders saying that the country's leader was an imminent threat.
Slobodan Milosevic wasn't even a hypothetical, long-term threat. So, why did we attack?