What are some political problems and wars caused by oil?

Example: some suspect that the US lead invasion of iraq was oild driven.What are some political problems and wars caused by oil?
I suppose that environmentalists look down on certain political parties who don't do anything to stop our dependence on oil. I don't know that there are any wars that were outwardly declared because of oil, but there have been wars where many have suspected that oil was the underlying reason. Honestly, if oil was a reason for war, then the first countries that someone should be declaring war on would be Saudi Arabia and Canada.What are some political problems and wars caused by oil?
Mideastern Muslims have a lot of money because of their oil reserves. That has caused a lot of problems.
Because if we don't have oil, our way of life is threatened. Instead of finding alternatives, some want to make sure we have access to middle east oil reserves. I think our best bet is to spend some money and develop alternative ways to fuel our lifestyle.