VICTORIES IN the war on drugs are rare, so it would be wrong to be too churlish about this week's arrest of 31 suspected cocaine traffickers based mainly in Colombia. Their capture is certainly a triumph of collaboration between Colombian and American law enforcement officials. Colombia's police chief has pledged that the suspects will be extradited to America, a fate that the country's traffickers have successfully avoided since 1991.

That said, some skepticism is called for. Colombian drug rings have been smashed before, with little obvious benefit. In 1990 Pablo Escobar, the leader of the Medellin cartel, was imprisoned, but the flow of cocaine was barely interrupted, and Mr. Escobar soon escaped from jail. In 1993 Colombia's security forces found Mr. Escobar and killed him, but the cocaine trade carried on. In 1995 it was the turn of the Cali cartel to see its leaders captured. Again, the cocaine business thrived.

Historians of the war on drugs cite two instances in which the smashing of drug gangs produced useful results. In the early 1970s international police caught up with the French Connection and its Turkish opium suppliers. This produced a street shortage of heroin; prices increased; addicts were forced to seek treatment. In 1989, similarly, Colombia's government launched an all-out war on the Medellin cartel, after the traffickers exceeded their usual arrogance and killed the ruling party's presidential candidate. Again, this pushed the street price of cocaine up, encouraging addicts to get medical help. But in both cases the price increases proved temporary. New suppliers quickly spotted a market opening.

In sum, three decades of hunting down drug traffickers has done little to curb drug abuse in America, and there is little reason to suspect that the latest "success" will prove different. Drugs reach consumers by too many routes, courtesy of too many shifting alliances of criminals, for even spectacular police successes to disrupt supply much. Donnie Marshall, the acting head of the Drug Enforcement Administration, talks up the value of Wednesday's arrests by saying, "Over time we dilute their talent pool." This defense of the war on drugs has the virtue of modesty. But it is hardly comforting.