Just a thought - perhaps Obama knows how unlikely diplomacy will be in this case but is going through the charade as part of a process which is designed to convince his supporters what a dangerous asshole Ahmedinejad actually is. One possible result being that when force is used it will only be after having demonstrably exhausted other ‘possibilities’, (change?) and only after the ‘obamamedia’ is used to the idea of presenting Ahmedinejad as a man with whom dialogue really is useless.