Because it generally did supply Iraq with intel and technology, weaponry through third parties,dual-use technology and know-how transfer. Limiting the discussion to strictly major weaponry as outlined by IPRI distorts the actual support given by the US to Saddam. Official numbers as outlined by IPRI are of course correct.
Yet, according to https://www.sipri.org/databases/armstransfers/sources-and-methods only covers:
IPRI covers only what it terms major weapons.
e.g. Artillery, Tanks, Satellites, Ships
It does not cover
other military equipment such as small arms and light weapons (SALW) other than portable guided missiles such as man-portable air defense systems (MANPADS) and guided anti-tank missiles. Trucks, artillery under 100-mm caliber, ammunition, support equipment and components (other than those mentioned above), repair and support services or technology transfers are also not included in the database.
It also only lists traceable transfers.
While initially, the support of Saddam was basically nonexistent, considering his role in the Soviet sphere of influence and his opposition towards Israel, this changed with the outbreak of the Iran-Iraq war (1982-1988). Iranian leaders like Khomenei believed Saddam got the green-light for the invasion from the US. Support for Iraq hereafter included:
- Removal from the State Departments List of State Sponsors of Terrorism in 1982, which helped to facilitate the trade of dual-use technology.
- Donald Rumsfeld meeting at least twice with Saddam in 1983 and 1984
- Diplomatic support (or non-condemnation), e.g. in the UN in relation to the use of chemical weapons
On Intel, tech and know-how transfer: According to Howard Teicher,
[T]he United States actively supported the Iraqi war effort by supplying the Iraqis with billions of dollars of credits, by providing U.S. military intelligence and advice to the Iraqis, and by closely monitoring third country arms sales to Iraq to make sure that Iraq had the military weaponry required. The United States also provided strategic operational advice to the Iraqis to better use their assets in combat ... The CIA, including both CIA Director Casey and Deputy Director Gates, knew of, approved of, and assisted in the sale of non-U.S. origin military weapons, ammunition and vehicles to Iraq. My notes, memoranda and other documents in my NSC files show or tend to show that the CIA knew of, approved of, and assisted in the sale of non-U.S. origin military weapons, munitions and vehicles to Iraq.
Further there were 60 US Defense Intelligence Agency officers sent to Iraq for training and know-how transfer during that time.The CIA shared Satellite imagery with Iraq on Iranian troop movement
On ABC-dual use technology: According to the 1994 Riegle report:
Records available from the supplier for the period from 1985 until the present show that during this time, pathogenic, toxigenic, and other biological research materials were exported to Iraq pursuant to application and licensing by the U.S. Department of Commerce. Records prior to 1985 were not available, according to the supplier. These exported biological materials were not attenuated or weakened and were capable of reproduction.
On spare parts and ammunition:
The Bear Spares program made sure that spare parts and ammunition were available to Iraq: According to Teicher:
If the "Bear Spares" were manufactured outside the United States, then the U.S. could arrange for the provision of these weapons to a third country without direct involvement. Israel, for example, had a very large stockpile of Soviet weaponry and ammunition captured during its various wars. At the suggestion of the United States, the Israelis would transfer the spare parts and weapons to third countries ... Similarly, Egypt manufactured weapons and spare parts from Soviet designs and provided these weapons and ammunition to the Iraqis and other countries.
This is all not to say that other countries did not support Iraq in a similar fashion, that the US was Saddam's biggest supporter/supplier or that the US government did not have an ambivalent relationship with Saddam through its different actors and branches.