"Iran...may not have been the United States' best friend in the past three and a half decades, but it remains a legitimate nation-state. It has a political system with a series of checks and balances and some level of accountability and debate. Importantly, Iran can be deterred. Ideology is certainly a driver behind Tehran's decision-making, but its national interests dictate much of its actions. These interests in turn do not always converge with those of the United States, nor do they always conflict."