The Dictator

The Opposition Leader
The Economy

I am not a person that has an in-depth knowledge of Africa or the African Continent and perhaps I am batting out of my league with this post. However, that is not the point as I am not intending to provide any analysis of the situation per se but rather pose a question or two.
The economy in Zimbabwe is spiralling out of control with inflation running at more than 1000% and this is forcing the government to print money (above picture) and this then puts even more pressure on the economy. It is sad that the Zimbabweans have gone from being the bread basket of Africa to being its biggest basket case.
The current leader is proud of being compared to Hitler and has gone on the record as saying he would like to be Hitler ten-fold. He is running an election campaign that is relying on violence to get the desired outcome. This has surprisingly brought out a little spine in the British government, the former colonial masters, who have publicly named the individuals that they believe are orchestrating the campaign violence.
The opposition leader, Morgan Tsvangirai, has pulled out of the run-off poll. This means a default win for Mugabe. Yet, Tsvangirai has a point in that the risks to people to come out and vote are high, particularly when one considers that Mugabe appears intent on keeping power by any means necessary. Reports of intensifying violence are increasing.
It seems abundantly clear to me that Mugabe is a tyrant and a dictator determined to do whatever it takes to cling to power. This includes not only running the Zimbabwean economy into the ground but also arbitrarily arrest, torture, and kill his own people if necessary in order to cling to power. The only difference that I see between Mugabe and Saddam Hussein is that there is no false claims about Mugabe having weapons of mass destruction and Zimbabwe has no oil.
So, here is my question:
Why is it that the US felt the need to go into Iraq to remove a nasty dictator and then call on the rest of the world to come into a coalition and support them, but they do not seem to feel there is any need to do the same thing with an increasingly violent dictator in Zimbabwe?
Call me a cynic but is it because there is no oil?