LAW enforcement makes for strange and occasionally uneasy alliances. Beginning in January 2007, according to a report from theNew York Times, a Colombian informant made contact with and began working with associates of Harold Mauricio Poveda-Ortega, a major cocaine trafficker. The informant was also working with agents from America's Drug Enforcement Administration (DEA), which has, in turn, been working with Mexican law enforcement in an effort to expand its role in Mexico's drug war. Over the next ten months, the informant would work his way up in the organisation, winning greater confidence and acquiring greater responsibility. Undercover agents, posing as pilots or other business associates, helped. All told, the law enforcement agents helped smuggle millions of dollars in cash, and helped coordinate a number of wire transfers. At one point they tested a 330kg shipment of cocaine for purity, in Dallas, before sending it on to Madrid (where it was seized by Spanish authorities foakley sunglasses, who had been tipped off by the DEA).

There is a strong argument for such cooperation. By tacitly allowing some traffic, of drugs or money, law enforcement officials could follow these transactions some way up the river in the hopes of nearing a source, or substantiating a legal case against him. That appears to be what has happened here. Mr Poveda-Ortega escaped a raid in 2008, but was captured in 2010, in Mexico City. Mexico has agreed to extradite him to the United States, and to that end, has prepared some documents. That includes the documents that the report is based on, which were originally obtained by emeequis, a Mexican magazine, and shared with the Times. The latter goes on:

Shown copies of the documents, a Justice Department spokesman did not dispute their authenticity, but declined to make an official available to speak about them. But in a written statement, the D.E.A. strongly defended its activities, saying that they had allowed the authorities in Mexico to kill or capture dozens of high-ranking and midlevel traffickers.

“Transnational organized groups can be defeated only by transnational law enforcement cooperation,” the agency wrote. “Such cooperation requires that law enforcement agencies — often from multiple countries — coordinate their activities, while at the same time always acting within their respective laws and authorities.”

At the same time, such collaboration makes many people uneasy—particularly in the wake of Operation Fast and Furious, the controversial programme from America's Department of Justice, under which federal agents working in the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) allowed known straw buyers in Arizona to make off with some 2,000 guns, several hundred of which have subsequently been recovered at crime scenes. There are, to be fair, major differences in the two. The most obvious is that money and drugs are not, in themselves, as dangerous as weapons. That was the glaring conceptual problem with Fast and Furious, which has been shut down and is being investigated by Congress. Secondly, the money-laundering operation described here depended on cooperation between American and Mexican officials, meaning that whatever the wisdom of the project, the judgment was mutual on the part of the respective law enforcement agencies.

The report also dramatises some of the challenges of Mexico's war against its drug-trafficking organisations, a daunting and seemingly intractable conflict in which gains by law enforcement are often offset by a corresponding setback or spasm of violence as the gangs battle for primacy against one another. It may be that this operation was crucial to the capture of Mr Poveda-Ortega foakleys, who had been a major supplier for Arturo Beltrán Leyva, a gang head who was killed in a raid in 2009. But as this paper explained in 2010, that victory for law enforcement triggered a bloody succession struggle within his organisation, and a turf war among the rival organisations. In the face of such a vicious circle, it is no surprise that law enforcement agencies are taking some risks.