But perhaps the most important measure of the programs' efficacy was issued just a few weeks ago, when the White House drug-policy office reported that "cocaine is widely available throughout most of the nation." The office offered similar assessments for heroin and marijuana.
"Yes, narcotics are readily available," said Anne Patterson, the assistant secretary of state for international narcotics enforcement. "But if we weren't doing these projects, the problem would be dramatically worse." The government spent more than $1 billion last year fighting drugs.
The successes included Colombia's extradition of 134 suspects to the United States on trafficking and other criminal charges during 2005, the most ever. The report also noted that Laos had reduced its opium poppy cultivation to negligible levels, and that Thailand, once a major producer, had "practically eliminated" drug production, though that point was also made in the 2004 report.
In singling out trouble spots, the State Department report focused on two countries in particular, Colombia and Afghanistan.
In Colombia, the United States has financed a multibillion-dollar antidrug program since 2000. Every year, thousands of acres of coca plant have been sprayed with herbicides; the department reported record spraying of 36,000 acres in 2005.
But each year, growers plant new bushes so quickly that for the past three years, acreage under cultivation has remained stable. As a result, the report said, "Colombia is the source of 90 percent of the cocaine entering the United States."
Congress is to debate the financing for the Colombia project this spring.
The antidrug campaigns have run for more than 25 years, but, officials acknowledged, traffickers have almost always been able to meet American market demands. Drug enforcement officials measure their success on small fluctuations in purity and price.
On Wednesday, an official pointed to a note in the report that said preliminary reports indicated that enforcement efforts "may have led to an increase in the U.S. street price of cocaine" and "a reduction in purity."
Afghanistan is the other country of major concern. About 30 percent of Afghanistan's economic activity is a result of opium poppy cultivation, which supplies about 90 percent of the world's heroin.
Ms. Patterson said intelligence information shows that poppy cultivation in Afghanistan was increasing this year. Last year, the administration warned that Afghanistan was "on the verge of becoming a narcotics state."
On Wednesday Ms. Patterson said at a news conference that controlling production in Afghanistan "is going to be a huge challenge" and "is going to take years and years and years." Most of the heroin produced from Afghan poppies is sold in Europe and Asia, not the United States.
Though the report did not address it, the administration remains gravely concerned about Evo Morales, the new president of Bolivia, who once led a major coca planters' union and has vowed to end the American-financed eradication programs.
Although Mr. Morales has not said what he intends to do, he has offered the paradoxical position that he will not impede coca cultivation but will fight drug trafficking. Government troops in charge of coca eradication have stopped work, awaiting orders.