...and presidents of both parties have ordered military action against nations that challenged the "petrodollar." This is not an easy issue to solve, but the solution can't be to murder innocents under the guise of fighting drugs or finding WMDs, etc.

"to sell you their oil cheap" was a simplification to fit within the reality of the strip. The actual real world issue is Venezuela selling oil for non-US currencies like the Chinese Yuan. Most oil in the world is only sold for US Dollars, which helps keep the dollar's value high...