All in the name of “means to an end”.  Saddam was habitually “crossing the line” WHILE he was being propped up by the Reagan administration,  WITH THEIR KNOWLEDGE. 1982 was when the infamous Rumsfeld meeting with Saddam took place,  when the US was taking Saddam’s side and putting most of their eggs in that one basket.  It seems that these things which are atrocities now were matters on which the US chose not to act or complain THEN.  Disgusting. 

To prevent an Iraqi collapse, the Reagan administration supplied battlefield intelligence on Iranian troop buildups to the Iraqis, sometimes through third parties such as Saudi Arabia. The U.S. tilt toward Iraq was enshrined in National Security Decision Directive 114 of Nov. 26, 1983, one of the few important Reagan era foreign policy decisions that still remains classified. According to former U.S. officials, the directive stated that the United States would do “whatever was necessary and legal” to prevent Iraq from losing the war with Iran.

The presidential directive was issued amid a flurry of reports that Iraqi forces were using chemical weapons in their attempts to hold back the Iranians. In principle, Washington was strongly opposed to chemical warfare, a practice outlawed by the 1925 Geneva Protocol. In practice, U.S. condemnation of Iraqi use of chemical weapons ranked relatively low on the scale of administration priorities, particularly compared with the all-important goal of preventing an Iranian victory.

Thus, on Nov. 1, 1983, a senior State Department official, Jonathan T. Howe, told Secretary of State George P. Shultz that intelligence reports showed that Iraqi troops were resorting to “almost daily use of CW” against the Iranians. But the Reagan administration had already committed itself to a large-scale diplomatic and political overture to Baghdad, culminating in several visits by the president’s recently appointed special envoy to the Middle East, Donald H. Rumsfeld.

Source: U.S. Had Key Role in Iraq Buildup (washingtonpost.com)

So Saddam is being sentenced to death for an act he carried out under the “care” of the United States.  We weren’t so concerned about his murderous ways then. I suppose that falls under the protection of the ultimate excuse: “That’s war”.