You conveniently disregard the fact that US and UK bombs and guns are killing innocent non-combatants on a daily basis.
You conveniently disregard the fact that most human shields are involuntary.
You conveniently disregard the fact that the US is a member of the UN security council and bound by the rules of the UN, rules it is currently ignoring, whereas Iraq is not a UN member and is not bound by those rules.
It's inconvenient, but you can't have an answer for everything.