The team of farm workers was almost cheerful as they toiled in the small field under the blazing sun, yanking up one coca bush after another. They were fresh off the helicopters that had dropped them in the middle of this guerrilla-controlled national park to uproot thousands of acres of the plant that yields the main ingredient in cocaine.
Hoover Vera, one of the workers, joked that never in his life had he expected to have bodyguards, a luxury usually reserved for Colombia's elite. "How can we not be safe with all these police around with so many guns," he said last month gesturing to police units resting in the shade of a tree.
Mr. Vera was one of 900 coca pickers who were the centerpiece of an ambitious government initiative meant to deal a decisive blow to Colombia's leftist rebels in their stronghold of La Macarena National Park, and to the cocaine trade that funds them.
But now, less than a month after a the operation began, a series of rebel attacks have led two-thirds of the 900 workers to resign over fear for their safety, and could throw the government's entire manual eradication program into doubt.
The latest attack on the operation came last week when rebel sharpshooters ambushed and killed six soldiers. The attack, the second in as many weeks, prompted President Alvaro Uribe, who was in Washington for trade talks, to order air raids on rebel camps hidden under the lush tree cover of the Macarena National Park.
The double-pronged strategy of simultaneously gaining military control over the park and wiping out the coca found there was announced in reaction to the Revolutionary Armed Forces of Colombia's, or FARC's, bloodiest attack on government troops in years, which left 29 policemen dead in December.
But analysts say the government may have underestimated FARC's resolve to hold on to this strategically important territory.
"The government took the [manual eradication program] into an incredibly complicated stage in a very abrupt way," says Ricardo Vargas, director of the Acción Andina think tank, which monitors antinarcotics strategies in the Andean region.
"Unfortunately improvisation in La Macarena could put the entire [manual eradication] program into question," Mr. Vargas adds. "After the latest rebel attacks, skeptics will start saying, 'Spraying is the only way.' "
That's the message from Sen.Juan Gomez Martinez, who has consistently defended the spraying option in the parks. "The latest events proved us right," he says. "The government has to rethink this policy and send in the [spray] planes."
Senator Gomez says any environmental damage from the spraying is recoverable. "You cannot recover a human life," he says.
For now, however, Mr. Uribe, who is up for reelection this year, may be taking a cue from the polls. A survey published Wednesday in the El Tiempo newspaper, showed nearly 60 percent of Colombians believe manual eradication is the best option in dealing with illegal crops.
US-funded aerial spraying has been the cornerstone of the Colombia's antinarcotics strategy for years. But coca is now planted in smaller, more compact plots often in the middle of acres of legal food crops, making spraying more complicated. And in national parks, where coca growers have taken refuge from the spray planes, aerial fumigation is prohibited to protect wildlife.
So where spraying is made difficult for political, environmental, or logistical reasons, the government is now sending in teams of manual eradicators, recruited from the millions of unemployed farm workers around the country.
Since the program began in earnest last March, the manual eradicators uprooted more than 76,600 acres of coca crops and aim to pull up as much as 100,000 acres this year - about half of all the coca in the country, says Victoria Restrepo, director of the government's voluntary manual eradication program.
While the US government bankrolls the aerial spraying, the manual eradication program is funded mostly from Colombia's national budget.
One Colombian official, speaking on the condition of anonymity, says US antinarcotics officials in Bogotá see manual eradication as "a threat to US [economic] interests in the aerial fumigation program," noting that most of the $200 million the US spends each year on the spray program goes to US firms contracted to provide pilots, mechanics, and herbicides.
A US Embassy official would only say that "the important thing is eradication in an effective manner." US officials have previously voiced concern about the dangers of having people pull up coca by hand in rebel-held areas.
Ms. Restrepo, however, defends the practice as more effective and less costly than aerial spraying, noting that while spraying kills one harvest, pulling out the plants eliminates the entire crop.
But she admits security is a problem, and as the program advances it gets more dangerous. "Last year the FARC barely knew we existed. We worked on crops near populated areas, the logistics were easier," Restrepo says. "But now the workers have to march for hours through open fields or in the jungle before reaching the coca, and that puts them at more risk."