BY SHANE HARRIS AND MATTHEW M. AID

"According to recently declassified CIA documents and interviews with former intelligence officials like Francona, the U.S. had firm evidence of Iraqi chemical attacks beginning in 1983. At the time, Iran was publicly alleging that illegal chemical attacks were carried out on its forces, and was building a case to present to the United Nations. But it lacked the evidence implicating Iraq, much of which was contained in top secret reports and memoranda sent to the most senior intelligence officials in the U.S. government. The CIA declined to comment for this story".

http://www.foreignpolicy.com/articles/2013/08/25/secret_cia_files_prove_america_helped_saddam_as_he_gassed_iran?page=full

Full Declassified Report

http://www.scribd.com/doc/163045562/Iran-Iraq-Situation-Report