Note that this has been widely-known that the US supported Iraq in various ways during the bloody eight-year Iran-Iraq War of the 1980s; these recently declassified files merely confirming it further. As Foreign Policy notes:
In 1988, during the waning days of Iraq’s war with Iran, the United States learned through satellite imagery that Iran was about to gain a major strategic advantage by exploiting a hole in Iraqi defenses. U.S. intelligence officials conveyed the location of the Iranian troops to Iraq, fully aware that Hussein’s military would attack with chemical weapons, including sarin, a lethal nerve agent.
The intelligence included imagery and maps about Iranian troop movements, as well as the locations of Iranian logistics facilities and details about Iranian air defenses. The Iraqis used mustard gas and sarin prior to four major offensives in early 1988 that relied on U.S. satellite imagery, maps, and other intelligence. These attacks helped to tilt the war in Iraq’s favor and bring Iran to the negotiating table, and they ensured that the Reagan administration’s long-standing policy of securing an Iraqi victory would succeed. But they were also the last in a series of chemical strikes stretching back several years that the Reagan administration knew about and didn’t disclose.
U.S. officials have long denied acquiescing to Iraqi chemical attacks, insisting that Hussein’s government never announced he was going to use the weapons. But retired Air Force Col. Rick Francona, who was a military attaché in Baghdad during the 1988 strikes, paints a different picture.
“The Iraqis never told us that they intended to use nerve gas. They didn’t have to. We already knew,” he told Foreign Policy.
And here is the most chilling part for me:
But the CIA documents, which sat almost entirely unnoticed in a trove of declassified material at the National Archives in College Park, Md., combined with exclusive interviews with former intelligence officials, reveal new details about the depth of the United States’ knowledge of how and when Iraq employed the deadly agents. They show that senior U.S. officials were being regularly informed about the scale of the nerve gas attacks. They are tantamount to an official American admission of complicity in some of the most gruesome chemical weapons attacks ever launched.
Needless to say, I’m pretty sure this is one reason the Iranians haven’t been very cooperative, in addition to the US-backed coup against their democratically-elected prime minister, Mohammad Mossadegh, in 1953, and our subsequent installment and support up of the authoritarian Shah thereafter. Given that many other Western government and firms also supported Iraq in its war, Iran’s cynical and isolationist foreign policy isn’t surprising.
This isn’t to leave its authoritarian government off the hook either, however; this merely allows them to find more legitimacy for their refusal to work with the US, a feeling that has in any case been mutual.