>> steve kleppe: it's tremendously important. in the supply chain, this is step one. and you'll find these type of clandestine labs closest to the coca fields themselves. >> logan: the piles of coca leaves you see here are the source of the cartel's vast fortune. inside these big barrels, the leaves are soaked with gasoline and toxic chemicals to make unrefined cocaine. there are thousands of labs like this across colombia. they're easy to build and easy to conceal. the commandos set a series of explosive charges throughout the makeshift structure, and directed us to a nearby coca field where we watched the jungle lab go up in smoke. it's a tiny but critical part of the super cartel's global enterprise. 200 miles to the north, the cartel bosses ran their daily operations from a string of small cafes and coffee shops in an upscale neighborhood in bogota. that's where luis sierra and other ice agents shadowed them for months. how difficult was it to run surveillance on this cartel? >> sierra: i'd say this was the most difficult surveillance that we've ever seen. these g