The first serious comprehensive attempt to produce such a framework was undertaken by Graham Allison in his book Essence of Decision (1971), and further refined by Allison and Morton Halperin (1972). Allison’s immediate focus in Essence of Decision was explaining why the governments of the United States and the Soviet Union did what they did during the Cuban missile crisis. With a nuclear exchange at stake, these were policies of particular importance, but Allison was aiming well beyond the confines of one case study. Essentially, he posed a broad question that cut to the heart of bureaucratic politics: Why do governments do what they do? In other words, how is policy made, and who determines or influences it? To provide general answers to these questions, Allison articulated three theoretical models.