I don't think we should say let's pay for the invasion with their oil, it's probably more accurate to say let's take their oil or steal it because when you say

I don't think we should say let's pay for the invasion with their oil, it's probably more accurate to say let's take their oil or steal it because when you say 'pay' it implies Iraqis asked for invasion(which they didn't) and you are talking of oil as payment.