I'm not sure that I follow that argument.

What opposition are you referring to ?

In the Iraq 'war' The US and Britain were the aggressors.

Sadam Hussein did not declare war but put up a defence against an illegal act. (no I am not defending Sadam)

There is no doubt that the 'war' was based on flawed intelligence on the part of both countries.

Perhaps, the fact that it was an invasion rather than a 'proper' war, has led people to believe that basic humanitarian principles do not have to be adhered to.