The US Senate didn't; they passed sanctions against Iraq in response to that, however the White House vetoed those, and sent Rumsfeld to "resume relations with Iraq" at the same time.There is no difference but do you think the US approved Iraq using chemical weapon against Iran?
There are plenty of articles from the time before the '03 Invasion backing this up.
A number of quotes from a 2002 Guardian article:
A 1994 congressional inquiry also found that dozens of biological agents, including various strains of anthrax, had been shipped to Iraq by US companies, under licence from the commerce department.
Now back to Sudan?Furthermore, in 1988, the Dow Chemical company sold $1.5m-worth (£930,000) of pesticides to Iraq despite suspicions they would be used for chemical warfare.