I once saw an episode of some political show on tv where an American was shot down in Iran and we were trying to get him out. We met with an Iranian diplomat asking for permission to come in and rescue the American before the rebels got to him. The diplomat was a bit skeptical saying "Why should we believe you? Your country has troops in Iraq on our Western border, troops in Afghanistan on our Eastern border, ships in the Persian sea directly below us, and bombers on our Northern area.... you have us surrounded."
As soon as he said that, i realized that it's true. Take a look:

With this said, do you think this would be a good plan to invade Iran? We would hit them from all angles, North, South, East, and West... forcing their military to fight on four different fronts. Maybe this has something to do with why Bush and his cronies chose to do what they did.
I'm not saying whether it's a good idea or not; i'm just simply asking a question.