The top US drugs official has said anti-drug efforts are having the best results of the past 20 years.
John Walters, head of the Office of National Drug Control Policy, said cocaine shortages had led to a jump in prices in 37 American cities.
Efforts on both sides of the Mexican border have disrupted the flow of all drugs into the US, Mr Walters said.
But he said it had not yet been proven if the results could be sustained over the long term.
Mexican traffickers extradited
Mr Walters was speaking as the US and Mexico work out the details of an aid plan - expected to total $1bn - for Mexico to help combat drug cartels.
About 90% of the cocaine entering the US comes through Mexico.
"What's happened for the first time in two decades is we now see widespread reports of cocaine shortages in the United States," Mr Walters said.
In 37 cities had reported, he said, "the l
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