Argumentum ad populum

Ignoring whether or not the world actually does, or how vehemently they might disagree, the rightness of a thing isn't measured at all by how many people think the thing is right.

The rest of the world actually doesn't disagree. Just look at what countries supported and participated in US conflicts. And there are countries who don't support openly, but behind the scenes with intelligence and logistics.

Because the US also happens to dominate the global economy for now. Soldiers from my country went to help the US in Iraq and Afghanistan too, and we all know why - because the country needs to suck up to US to strengthen its position relative to the neighbors. Moral reasoning didn't even enter the picture.