Exxon Revenue for 2006: $366B
Venezuela GDP (at PPP): $335B (2007 estimate)
Chavez's empty threats to stop sending oil to the US are no different than a child saying he'll hold his breath until he turns blue. Seems that half of Venezuela's oil output can only be refined in the US at present.
Furthermore, Chavez's disastrous policies have lead to Venezuela now importing $40B a year in food and dipping into reserve currency to do it.
One company, that also pays more in US taxes than the entire bottom 50% of individual income taxpayers (note: I haven't researched that statistic myself, but it looks plausible), is certainly not someone you should piss off it you are a Petrodollar-dependent dictator who cannot even provide for your own people!
