As stated above, Chavez has had increased relations with both China and Russia, and has purchased Russian weapons. However, in addition, he has traveled to Iran to no doubt try to strengthen relations with a prominent U.S. security threat. While Chavez is working on Venezuela's relations with Iran, Bolivia is doing the same.
Bolivian President Morales has traveled to Tehran to meet with Iranian President Ahmadinejad on several occasions, only make their alliance stronger. Unlike Chavez's talks with Iran, Morales' talks have had significant consequences. Most importantly perhaps, is the transfer of Bolivia's only Middle Eastern embassy to Tehran from Cairo. In addition, the talks have led to an investment of over one billion dollars to Bolivia's natural gas industry from Iran. What kind of implications does this warrant for the U.S.?
If relations with Latin American countries were perfect, these talks between Iran, Venezuela, and Bolivia would already be unnerving - no one wants their enemy making friends with the backyard neighbors. However, U.S. relations with Latin American countries have historically been on shaky ground. Currently, the only strong alliances the U.S. has in Latin America are with Mexico, Costa Rica, and Colombia due to the five billion dollar per year aid the country receives to combat the illegal narcotic trade. Other moderate alliances, if you choose to refer to them as so, are with moderate left wing countries, such as Argentina, Brazil, and Chile. However, there are many far left wing countries that the U.S. does not have great relations with. These include Venezuela, Cuba, Bolivia, Nicaragua, and Ecuador. The numbers are not looking good for the U.S.
With numbers working against the U.S., Iran, Russia, and China's involvement in Latin America could have severe implications for U.S. security. Although Russia and China have had previous dealings in Latin America, Iran's involvement is fairly new. With tensions ever increasing with Iran, and Iran's relations with Latin American countries only strengthening, the U.S. could be treading into very dangerous waters.
Beatriz Lecumberri, "Chavez Defies U.S. by Dealing with Russia, China," Defense News.