Another factor is that politicians need to get elected, and want to get elected over and over. Voters want conflicting things:

• Cheap oil, and a continuing good economy.
  
• No war about oil (or anything else).

But as Jerome points out, there is widespread denial about the coming oil shortage. And obviously people don't like war. The fact is that a result of our demand for oil is our support for extremely questionable political arrangements all over the Middle East, which lead to frustration amongst a big part of the population there. This inevitably leads to what we today call terrorism.

So what is a politician to do? Support global peace and deny the reality that this will lead to a massive oil shortage in the short run? Or support--openly or with a wink--the war to maintain the oil supply (for as long as possible)?

I do not personally believe that European leaders, any more than American Democratic leaders, support the idea of a fundamentalist Muslim world that extends from India to Spain--as advocated by at least some Islamists.