Who supplied Saddam with chemical weapons?

""But the U.S. record on enforcing this norm is not perfect. It's still not clear what exactly happened during the brutal 1980s war between Iran and Iraq, but human rights groups have accused the United States of turning a blind eye when Saddam Hussein, then an ally, used chemical weapons against Iran as well as his own people. Iraq's Al-Anfal campaign, in which the country deployed chemical weapons as part of an effort that killed as many as 180,000 ethnic Kurds, almost five times as many people as have died throughout Syria's 20-month war.""