The rising street price of cocaine in the US shows that its policies in Latin America are working, a senior US drugs policy official has said.
Colombia has received $3bn in US aid for the fight against drugs
John Walters said the price of a gram of cocaine had risen 19% in seven months, and its purity had fallen.
Critics say the price rise is just a temporary blip, and the war on drugs has made no real progress in 20 years.
The US has given over $3bn (£1.8bn) of mainly military aid to Colombia, the source of most of the world's cocaine.
The aid was given under Plan Colombia, which started in 2000 and ended this year. A second version of the plan is currently in discussion.
The US Congress has recently approved a $740m Andean Counterdrug Initiative for South America.
Speaking to the BBC, Mr Walters - head of the White House Office of National Drug Control Policy - denied accusations that US anti-drugs policies focused only on tackling the supply chain.
He said the government spent more each year on treating its addicts than it did on military aid to countries such as Colombia to fight the drug producers.