Medellin, Colombia - It has been the biggest US military aid programme outside the Middle East, but 14 years and $9.3bn after its inception, many analysts believe Plan Colombia failed to meet its stated objectives.
Security in much of the country did improve, however, during the course of the counter-narcotics campaign.
Former US President Bill Clinton and his Colombian counterpart Andres Pastrana formally initiated the programme in 1999-2000, with the US Congress approving $1.3bn in initial aid for counterinsurgency and counter-narcotics operations.
The campaign intensified with the election of far-right President Alvaro Uribe in 2002. He declared an all-out war on Marxist FARC fighters who were active in the drug business, while pushing later for the demobilisation of right-wing paramilitaries.
The costs of the war were, and are, extremely high. More than 5.7 million Colombians have been internally displaced in decades of conflict that has claimed more than 215,000 lives.
As of 2013, the US was providing Colombia with more than $310m in annual military and economic aid, according to the Washington Office on Latin America, a significant decline from previous years. But it's still enough to make Colombia the largest recipient of US military aid in Latin America.
The Plan's initial official objective, to reduce by half the amount of cocaine produced in Colombia in the first five years, failed, said Juan Vargas, a professor at the University of Rosario in Bogota who studies Colombia's conflict.
Helicopters sprayed toxic herbicides across rural regions attempting to destroy coca plants, with unintended consequences. "It was bad for health outcomes in the places where they were spraying, creating skin diseases and rashes," Vargas told Al Jazeera. "It increased violence where there were eradications because the rebels didn't want to lose their sources of finance."
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'A failure in every respect'
Amnesty International went further, stating that: "Plan Colombia is a failure in every respect. Human rights in Colombia will not improve until there is a fundamental shift in US foreign policy."
Others beg to differ, arguing that the campaign played a key role in improving security, bringing Colombia back from the brink of total chaos. The country was facing 30,000 killings a year in the early 2000s and large sections of territory were outside the state's control.
Uribe, who expanded military operations linked to Plan Colombia as part of his so-called democratic security plan, left office in 2010 with an 80 percent approval rating, largely due to safety improvements.
"The results were impressive," Gustavo Duncan, a professor of political science at EAFIT University in Medellin who specialises in drug trafficking, told Al Jazeera. "I'm critical of Uribe in many respects, but I have to say he did a good job in leading the war.
"There are still a lot of problems with guerrillas, illegal mining, et cetera, but the state improved its capacity to rule. Fifteen years ago, if you went to the southwest of the country, there was paramilitary or guerrilla rule; they were the state. Today, there are still militias and mafias, but the state is there."
Uribe's legacy continues to loom ahead of Sunday's presidential election. Critics say he could act as a kingmaker or puppet master, given that his chosen candidate, Oscar Zuluaga, is leading in most polls.
Zuluaga has promised to end negotiations with the FARC, a hallmark of current President Juan Manuel Santos' administration, in favour of a full-throttle return to military action.
Santos served as defence minister under Uribe, but bitter animosity has developed between the erstwhile allies due to Santos' support for negotiations. Campaign posters for Zuluaga feature the candidate standing beside Uribe, implicitly linking the two politicians in the minds of voters.
"Uribe's enduring popularity with the electorate is in large part due to the tangible improvements to the security landscape achieved during his presidency," Matt Ince, a fellow at the Royal United Services Institute who studies Colombia, told Al Jazeera. "There was systemic progress in security reform, in part supported by the US through Plan Colombia."
On the streets of Medellin, a city once plagued by drug-related violence, all residents interviewed by Al Jazeera supported Plan Colombia.
"I would like to see more security help [from the US]," Francisco guerrillas, a delivery driver, told Al Jazeera. "If Uribe didn't go against human rights, then his campaign [battling FARC rebels] couldn't have worked."
Air conditioner technician Johay Hernandez echoed that view. "We need help [from the US and other countries] at this moment, as we can't do it [improve security] by ourselves."
Part of Plan Colombia, Ince said, involved pushing fighters away from major population centres like Medellin into "peripheral regions". These areas, which contain fewer voters than major cities, faced the worst human rights abuses associated with Plan Colombia.
Of the killings and corrupt dealings linked to military assistance deals, the most infamous was the "false positives" scandal, in which an estimated 3,000 innocent rural residents were killed by security forces and then posthumously dressed in guerrilla uniforms.
Many analysts tie these killings to the "body count mentality", which gave battalion commanders incentives to increase the number of dead guerrillas. "Pressure from the US to show empirical results in counternarcotics and counter-terrorism was one of the most perverse aspects of the mentality" surrounding Plan Colombia, said Arlene Tickner, an international relations professor at the University of the Andes in Bogota.
Security in many parts of the country improved significantly during the course of the Plan, Tickner told Al Jazeera, but this has more to do with improved local policing strategies in Bogota, Medellin, and later Cali, than in major military operations. The demobilisation of right-wing paramilitaries in 2005 also helped, she said.
From Colombia to Mexico
The plan decreased the amount of Colombian land used in coca cultivation, but the price and purity of drugs on US streets - key figures for measuring the effectiveness of counternarcotics operations - remained virtually unchanged.
In the 1990s, large-scale Colombian crime gangs, including the infamous Medellin and Cali cartels, dominated the world's cocaine market by producing industrial quantities of coca on large plantations and controlling distribution to the US and Europe.
The bulk of the value-added business moved to Mexico. These former groups [in Colombia] that were ... engaged in counterinsurgency basically became armed local mafias.
Plan Colombia helped change that, fracturing the large cartels. The biggest beneficiaries of this move, however, were Mexico's vicious gangsters.
In the 1990s, Mexican cartels were hired by Colombian criminals to help move product across the US border. Following the fracturing of Colombian syndicates, Mexican mafias became the dominant criminal forces in the hemisphere, outsourcing production to diffuse groups in Colombia and other South American countries.
"The bulk of the value-added business moved to Mexico," Vargas said. Like drug production itself, demobilised paramilitaries that once operated under the banner of the AUC (United Self-Defence Forces of Colombia), also fractured, the professor said. "These former groups that were sort of engaged in counterinsurgency basically became armed local mafias controlling cattle ranching, illegal mining, trade and other activities. Today, the areas of worst violence are usually near resource developments," particularly in Colombia's border regions, he said.
Despite these problems, US officials routinely tout Plan Colombia as a model for successful counterinsurgency campaigns, and the two frontrunners in Sunday's election both enthusiastically support the initiative.
A Colombian politician running against US military aid wouldn't have a chance of becoming president, and US officials are keen to expand the programme.
David Petraeus, the former head of US Central Command, and Michael O'Hanlon of the Brookings Institute advocate "greater Colombian involvement in training and mentoring the security forces of countries like Panama, Honduras, El Salvador and Guatemala so that these highly troubled states can make the kind of headway we have seen in Colombia over the past dozen years".
Follow Chris Arsenault on Twitter: @chrisarsenaul