Where have I heard this before? Ah yes . . . 9/18/2002, Donald Rumsfeld - "We do know that the Iraqi regime has chemical and biological weapons. His regime has amassed large, clandestine stockpiles of chemical weapons -- including VX, sarin, cyclosarin and mustard gas. ... His regime has amassed large, clandestine stockpiles of biological weapons—including anthrax and botulism toxin, and possibly smallpox." ... Good thing we are just as sure this time.
Certainly US knew Saddam had chemical weapons. He killed a lot of Kurds with them, but that was "wrong" - I.e. he did not have US's OK, like using them against the Iranian soldiers in the Iran/Iraq war did.
Those Iranian soliders were constantly moving* so gassing them needed real time location data - which the US satellites supplied as US was still quite angry with Iran for holding many US citizens, even diplomats, for about a year. Here is photo of the famous handshake between Rumsfield and Saddam taken 20 December1983, where US agreed to help Saddam, who had long been supported by the US CIA as he keep Iraq free of terrorist who might do damage to US interests in the Middle East.
Note the date in the embedded text from NYT's article of when the Iranian soldiers were gassed - Once Saddam got real time accurate location data about were Iranian troops were concentrated, he soon used it (two days after getting real time data download terminal set up). With US real time US satellite targeting data supplied just after (or during?) Rumsfield's second visit to Saddam the gas attacks were successful and Saddam basically won the Iraq/Iran war, much to US's delight. I.e. the Iranian troops who had crossed the river in the long disputed boundary area, which served as the de-facto boundary, had captured a few producing oil wells, but with real time targeting data, Saddam cut off the invador's supply lines and they retreated back across the river into Iran.
Its a deal: You get real-time targeting data, we get revenge on Iran.
Saddam made the same mistake that every CIA installed or supported dictator, except the Shaw of Iran, did. I.e. grew "too big for his britches" and bit the hand that feed him. In Saddam's case the mistake was very serious - he threatened to destroy the PetroDollar system by selling his oil for currency other than dollars. Saudia Arabia, one of the world's worst dictatorial regimes, especially for women to live under, was firmly supported by US and did the US's bidding. So first thing that happen after Saddam got out of line was the Saudi oil was pumped at more than the sustainable capacity (Their wells were damaged, and production levels, still had not recovered.**) That flood of oil drove the price down well below Saddam's cost of production - actually for a few weeks the price of oil was less than $10/ barrel! Saddam effectively said to CIA: "I'm sorry, I only sell oil for dollars." but the damage was done - he was no longer a dependable puppet for the CIA and had to be replaced.
In his old age, even when long out of power and very sick, the CIA leaned on Egypt to see that the Shaw of Iran got the very best of medial care in one of Egypt's military hospitals.
Moral of all this for CIA dictators to learn, is never get out of line. Your britches are not as big as the CIA's.
During the cold war, the CIA destroyed ALL of the developing democracies in South America and installed smarter dictators, none of whom got out of line. They started by killing Salvador Allende, the democratically elected president of Chile, who open declared himself to be a communist. These local dictators did not trust or like each other, so the "terrorists" who wanted return to democracy, and 50,000 died fighting for it, some times could get shelter by crossing the border, where if they keep quiet they could live - local dictator did not return them.
The CIA did not like that as many in South America did hate the US (Yankee go home, etc.) and would again vote for communists if given the change to vote. So CIA with its good computers and data base and spying agents, set up Operation Condor (I'll let you read about it at wiki as this post is long already but basically it kept tabs on where the "evil democracy lovers" were.) Fortunately, from the POV of South Americans wanting a return to democracy, the US got its hands full with the Vietnam War, and could not give as many, jeeps, tanks, water cannons, tear gas cartages etc. to their S.A. dictators so democracy slowing returned. It is interesting, and very well known in all of S.A. that via supported right wing locals, Allende was killed on 11 September - that CIA made 9/11 killed more than 10 times as many as the US suffered in its "9/11."
The exact number of those who died for democracy is not known, as many thousand were drugged in jail, loaded into US supplied helicopters, and dumped into the sea. They are called the "disappeared." Women freedom lovers were repeated raped in jail and allowed to live a few months after the baby was born, before being killed. The baby was given to childless couples who supported the dictators. Now several hundred middle age Chilians know they are not biologically related to the parents. Usually they lean this via need of a transfusion, which neither of their "parents" can give. There is even a DNA data base now, where parents of the "disappeared" can give samples of their DNA for those who want to learn who their real mother was.
* This also had the side effect of clearing mine fields, which amazingly to westerners, these "soon to be martyrs" very willing did even when there was no danger of being gassed.
** Under ground oil is in porous rocks. If it is removed more rapidly than it can flow in towards the well pipe from more distant parts of the oil deposit, then those rocks collapse and the max extraction rate from that well is greatly reduced. - More wells need to be drilled to get access to the oil that once flowed from the damaged well.