The U.S. government may be considering military action in response to chemical strikes near Damascus. But a generation ago, America's military and intelligence communities knew about and did nothing to stop a series of nerve gas attacks far more devastating than anything Syria has seen, Foreign Policy has learned.

...

The Iraqis never told us that they intended to use nerve gas. They didn't have to. We already knew," he told Foreign Policy.

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.

In contrast to today's wrenching debate over whether the United States should intervene to stop alleged chemical weapons attacks by the Syrian government, the United States applied a cold calculus three decades ago to Hussein's widespread use of chemical weapons against his enemies and his own people. The Reagan administration decided that it was better to let the attacks continue if they might turn the tide of the war. And even if they were discovered, the CIA wagered that international outrage and condemnation would be muted.

In the documents, the CIA said that Iran might not discover persuasive evidence of the weapons' use -- even though the agency possessed it. Also, the agency noted that the Soviet Union had previously used chemical agents in Afghanistan and suffered few repercussions.

...