BOGOTA, Colombia -- In the South American war against cocaine traffic, Colombia is only one of many strategic theaters where traffickers enjoy a big advantage over anti-drug forces. Even if authorities could win the battle in Colombia, they could still lose the war.

New U.S. aid for South America, proposed this week by President Bush, is unlikely by itself to improve bleak prospects for stopping cocaine at its origins.

In interviews over the past several months, numerous officials near the front lines of the South American war have underlined a common concern: The continent's rugged geography, weak institutions and needy peoples give cocaine traffickers almost unlimited opportunities for exploitation. Despite enforcement crackdowns like the current one in Colombia, officials agree, South American cocaine traffic will probably thrive as long as there are multibillion-dollar markets for the illegal product in the United States and Europe.

"I see law enforcement as buying time for demand-reduction programs in the United States to take hold," one Drug Enforcement Administration official said.

The Colombian blitz against traffickers by President Virgilio Barco Vargas began Aug. 18, the same day that assassinations of a leading presidential candidate and the police commander in Medellin triggered public outrage over violence by the Medellin drug cartel.

How long the enforcement campaign keeps its momentum depends in part on how long the public outrage lasts, many Colombian analysts say. The storm might well blow over if the Medellin traffickers adopt the more discreet tactics of the rival Cali cartel, which favors bribery and useful connections over assassinations and terrorism.

If President Barco's battle results in a temporary reduction of cocaine moving out of Colombia, that might even be profitable for Colombian traffickers. Assuming that a curtailed supply could not meet U.S. demand, the shortage would force up drug prices and profits.

"The whole interdiction theory is based on economic fallacies," a European diplomat said. "If you stop a ton, what you actually do is put up the price of cocaine. The Medellin cartel certainly doesn't suffer."

Others in the Wings

Any traffickers caught and convicted in the Colombian crackdown would enjoy no windfall profits, of course. But even if some of the cartel kingpins were arrested, they would soon be replaced from the ranks of middle-level traffickers, some officials say.

Others contend that the imprisonment of major traffickers will dissuade would-be drug lords from expanding. But in a continent where most people are poor, it is hard to calculate how many will risk their freedom for the lure of easy millions.

Should the battle rage on, and should the Colombian government eventually win, the control centers of cocaine trafficking undoubtedly would shift to other South American countries. Colombia has nothing that is essential for the production and smuggling of cocaine.

"There is no reason why they couldn't do it somewhere else," the European diplomat said.

Up to 80% of all cocaine that reaches the United States is refined in Colombia, but less than 20% of the coca leaves used in the refining process are grown here. Increasing amounts of cocaine hydrochloride, the purest form of the drug, are already being produced in Peru and Bolivia, where most coca leaves are grown and where traffickers would be eager to fill any temporary gap in the flow.

Eyes on an Opening

Bolivian traffickers have long been looking for the kind of opening that the crackdown on Colombian traffickers might provide.

"The Bolivians are getting tired of getting the short end of the stick with the Colombians," a DEA agent in Bolivia said.

President Bush's anti-drug proposal includes $260 million in additional foreign aid, the first installment in a $2-billion plan for fighting cocaine production in Colombia, Bolivia and Peru. But increased enforcement pressure in all three countries cannot dry up production, because Brazil and Venezuela are also beginning to make cocaine hydrochloride.

Enforcement officials in Colombia often say that the only way to control the traffic in South America is to eradicate coca and replace it with legal crops. And that is what U.S. policy is aiming for.