The futility of Colombia’s two-decade air war on the cocaine trade was laid bare on Thursday when the government, following President Juan Manuel Santos’ recommendation, agreed to halt the aerial spraying of coca crops with the herbicide glyphosate — a pillar of Plan Colombia, the multibillion-dollar U.S. aid package to fight drug trafficking.

Drug war opponents and environmentalists have long panned the use of aerial spraying in Colombia. Ironically, though, it’s the U.S. government that recently shed light on the policy’s impotence. The U.S. Office of National Drug Control Policy announced last week that the cultivation of coca, the main ingredient in cocaine, had spiked 39 percent in 2014 over the previous year — despite the U.S.-funded aerial spraying program that has fumigated 4 million acres of crops at a cost of nearly $2 billion since it began in 1994.

Despite the dismal eradication numbers, however, two other factors have contributed more to Colombia’s about-face.

Earlier this month the Colombian health ministry recommended the suspension of the government’s aerial fumigation efforts after the World Health Organization in March warned that glyphosate is “probably carcinogenic.” The WHO pointed to evidence that herbicide produces cancer in lab animals.

“I am going to ask the government officials in the National Drug Council at their next meeting to suspend glyphosate spraying of illicit cultivations (of coca),” President Santos said last week. “The recommendations and studies reviewed by the Ministry of Health show clearly that yes, this risk exists.”

Ongoing peace talks between the Colombian government and FARC rebels — a more than two-year-long effort to end the civil war that has afflicted the country for five decades — likely also played a role in Thursday’s announcement. Aerial spraying has been widely used in the country’s south where there are swaths of rural land and a stronghold for the rebel group, which the government accuses of financing itself with drug money. During talks last May, Santos and FARC leaders agreed on a plan to tackle the drug trade. The plan rests largely on FARC demands to halt aerial spraying as part of any final peace process.

By most accounts, aerial spraying in Colombia has been costly and ineffective. In recent years violent protests by Colombian farmers, who have complained of skin irritations and genetic abnormalities that they say are linked to glyphosate, have temporarily halted aerial spraying in certain regions. And Colombian researchers have found higher rates of miscarriages in places exposed to the spraying.

For decades Colombia has seen aerial spraying as the most reasonable weapon against coca in remote, mountainous areas that typify Colombia’s south — difficult terrain that is otherwise difficult to access.

“It has done so simply because it doesn’t have a presence of the government on the ground in these areas,” said Adam Isacson, a security policy analyst at the Washington Office on Latin America. “It has chosen to anonymously fly overhead, often with U.S. contract pilots doing the spraying.”

Colombian drug policy officials now have until Oct. 1 to cobble together a new plan to combat coca growing. The country’s Advisory Commission on Drug Policy, before Thursday’s announcement, presented Santos with recommendations focused on a public health-based approach. Among its proposals, the commission suggested that Colombia create a drug policy agency to coordinate all aspects of drug interdiction, according to the Colombian news website La Silla Vacía.

The commission also suggested that the government expand needle exchange programs and access to the medication Naloxone, which has been shown to decrease opioid-related deaths. Crop fumigation, the commission added, has been too costly and ineffective. To eradicate one hectare (1.4 acres) of coca, thirty hectares need to be fumigated, at a cost of $2,600 per hectare.

“Now it’s up to Colombia to govern its own territory,” Isacson said. “If it uses this opportunity, an opportunity that a peace accord may provide within the next year, to actually bring government services we as Americans take for granted into those parts of rural Colombia, then you are going to see a sustained reduction in coca growing and organized crime activity.”

With news wires