In Bolivia, another nation that has cut off most US cooperation, information from neighboring countries indicates the chiefs of some Mexican and Colombian drug cartels are moving to Bolivia to evade pressure from police, the Drug Enforcement Administration's intelligence chief Rodney Benson told a committee assessing US aid funds for the Andean region.

Meanwhile, Venezuela continues to be the main launch point for regional cocaine transport en route to Central America and then Mexico and the United States, though only one percent of the cocaine Bolivia produces ends up in the US market, the official said.

"Clearly, Venezuela is becoming more significant for drug trafficking organizations," Benson said.

"Right now we have one agent in the country. We need to continue to build with authorities there... but clearly we've taken several steps back," Benson said. And "I don't know the reasons why," he stressed.

It is not, in any case, a great surprise.

Politically, Venezuela is the United States' biggest problem in Latin America, due to its ties with Iran, Syria and Cuba. It also constantly tries to counter US influence with its own leftist cooperation programs.

Venezuelan President Hugo Chavez -- who is seeking reelection next year -- accused then-president George W. Bush of being involved in the short-lived coup that ousted him from office briefly in April 2002. The countries have tense bilateral ties, as do the United States and Bolivia.