The U.S. State Department, in the immediate aftermath of the incident, took the official position that Iran was partly to blame. A preliminary Defense Intelligence Agency (DIA) study at the time reported that Iran was responsible for the attack, an assessment which was used subsequently by the Central Intelligence Agency (CIA) for much of the early 1990s. The CIA's senior political analyst for the Iran-Iraq war, Stephen C. Pelletiere, co-authored an unclassified analysis of the war which contained a brief summary of the DIA study's key points. Pelletiere claimed that blue discolorations around the mouths of the victims and in their extremities suggested that a blood agent using cyanide was used in the attack at Halabja, and that only Iran was known to have used blood agents during the war. No proof that Iran had previously used hydrocyanic gas, as asserted by the DIA, was ever presented.