Its shame that your thinking on such a domestic scale, Capitalism is one country causes poverty in another.
US capitalism relies on the so called "free" market. When countries try to nationalise there resources, this equals a reduction in the size of the free market. The Us don't like that, and we are left with a superpower rampaging around the world "liberating".
Did it to Iran
Did it to Iraq
Did it to Congo


I am in no way a communist, but i am however anti-capitalist.
I dont truely believe Marx was a Marxist. He did not explain really how the sytem of communism would work, he merely explained the great injustice that capitalism is. I agree with his summation that capitalism is indeed a robbery system.
The reason : The Labour Theory of Value.
I dont have the time or the inclination to explain such a lengthy theory
however, if you ahve time to read
http://www.marxism.org.uk/pack/economics.html