Personally that's all the American's are good at "The Blame Game"
Transocean (Swiss company) operated the rig and upto 2007 they had a very good safety record, then they merged with GlobalSantaFe Corporation (a US company) and things started going down hill.
BP Exploration leased the Deepwater Horizon from Transocean in 2008.
Also understand that these drill companies are pushing the boundaries when it come to deep water drill, resulting in greater and great depths, and perhaps have push the boundaries too far regarding the technology to support equipment at such depths.
As desantnik said, if the American's weren't so reliant on oil, perhaps the cost/profit/risk of companies like BP pushing the boundaries too far too quickly, they might have been more measured in their approach and perhaps something like this may not have happened.
But who ever was responsible (not only BP), 11 people died, an eco system is being effected and OB isn't helping matters by making his campaign stance (perhaps for re-election)........ When solutions are required