I think this Israeli think tank report sits best here, especially Venezuela is centre stage with Iran and then there's Hezbollah:http://www.terrorism-info.org.il/mal.../iran_e163.htm

It ends with:
Iran's activities in Latin America and its readiness to carry out terrorist attacks on American soil (manifested by the attempted assassination in Washington of the Saudi Arabian ambassador) led Roger Noriega (added an AEI analyst) to the conclusion that "Tehran's activities near our homeland constitute a very real threat that can no longer be ignored." (ITIC emphasis) Despite with the grave assessments of the Iranian threat as expressed in a number of expert testimonies before Congress, certain members of the American administration are of the opinion that Iran's influence in Latin America is limited and that the United States can minimize it.
Not exactly an impartial review; Israel and those who lean a certain way maybe convinced.