Watch part two
At the end of October, the US quietly signed a deal with Colombia, its strongest ally in the region and the biggest recipient of US military aid in the hemisphere.
The agreement grants the US access to seven Colombian military bases for 10 years.
The event went practically unnoticed in Washington. But it raised a storm of protest from South American governments threatened by the specter of US military intervention in the region.
Alvaro Uribe, the Colombian president, and the Obama administration have cast the deal is a mere extension of the US "war on drugs" through the decade-old Plan Colombia.
But as Hugo Chavez, the Venezuelan president, declared that he was preparing for war, and tensions mounted at the Colombia-Venezuela border, Fault Lines traveled to Colombia to investigate why US access to the bases is a cause for so much consternation.
This episode of Fault Lines airs from Thursday, December 10, at the following times GMT: Thursday: 0600, 1630; Friday: 0130, 0830; Saturday: 1130, 2330; Sunday: 0630, 2030; Monday: 1430; Tuesday: 1230, 1930; Wednesday: 0300.