How did the US support of Iraq from 1980-89 contribute to the current war?

I have been assigned to read a book for a seminar class on this subject and I was surprised to learn that during this period the US government provided immense covert and overt assistance to Iraq for a variety of reasons (mostly to create a client-patron relationship after the US lost Iran in 1979). I was wondering how this support affected the 2nd gulf war?