you didnt get it.
doesnt matter whether Iraq is part of opec, if they were a US client they have the next largest reserves after Saudi Arabia and could easily affect world prices by dumping oil on the market - thereby making Opec irrelevant. (Just like the Saudis did in the mid 80s, which had major repercussions on the Russian economy that was dependent on hard currency from their oil - as well as Texas and Alberta oil for that matter)

I suppose the order to secure the oil ministry while all the other govt bldgs were being looted was pure coincidence.

- in any colonial war - eventually the colonialists have to go home.