Colombia's cocaine production fell by nearly 25% in 2011 from the previous year, and was down by more than 70% since 2001, according to the White House. A report released this week by the Office of National Drug Control Policy suggests that the Andean country once known as the largest producer of cocaine has scored a remarkable victory. That's great news, if indeed the latest estimates are accurate.

But the report is at odds with a United Nations survey released last week that concluded that Colombia's cocaine production remains virtually unchanged, dropping by a mere 1% since 2010. That's a significant and troubling discrepancy. The United States and the U.N. are the only two sources for cocaine production estimates.

Whose numbers are accurate? U.S. officials suggest the conflicting estimates reflect different reporting techniques. While both use satellite imagery as well as on-the-ground monitoring and seizures of cocaine, the U.S. says it uses higher resolution satellite images than the U.N. and therefore has a more accurate assessment of cocaine production. American officials also say the U.N. is not taking into account the fact that new coca crops are yielding less of the raw material for cocaine. On the other hand, questions have been raised about the fact that the U.S. is estimating that 83,000 hectares were used to cultivate coca in 2011, far more than the United Nation's estimate of 64,000 hectares. Yet the U.S. report finds that more land is yielding less cocaine.

The U.S. report also doesn't explain why Colombia's neighbors aren't sharing in its success. Output is up in both Peru and Bolivia, which are now the world's top two cocaine producers. That's hardly a victory, and more likely an example of what experts refer to as the balloon effect: Squeeze a balloon in one place and it will expand in another. The Obama administration insists that the uptick in those two countries is not enough to offset the drop in Colombia's cocaine production. Meanwhile, drug violence continues unabated in Mexico and Central America, as South American cocaine travels north.

No one disputes that cocaine production is down in Colombia from a decade ago. Both the U.N. and the U.S. reports indicate a decrease of more than 50% since 2001. This week's numbers are encouraging. But we'd like to see a more thorough explanation of how they were compiled to guide U.S. counter-narcotics policy in the future