Explosives experts wearing heavy body armor light a fuse and take cover behind a concrete-reinforced trench. "Fire in the area!" a commando shouts before a deafening blast ricochets across the Andean foothills and sends a plume of brown smoke 30 meters (100 feet) high.

Such drills have intensified for Colombia's military, one of the most battle-tested in the world, as it tries to control skyrocketing cocaine production that has fueled a half-century of war with leftist guerrillas.

After six straight years of declining or steady production, the amount of land under coca cultivation in Colombia began rising in 2014 and jumped 42 percent last year to 159,000 hectares (393,000 acres), according to the U.S. government. That's an area twice the size of New York City, and after much production shifted to Peru over the past decade, the United Nations said recently that Colombia is once again the world's largest supplier of the drug.

The military training exercises simulate the charges that troops typically use to blow up land mines protecting coca crops in areas dominated by the Revolutionary Armed Forces of Colombia, the rebel group known as the FARC. Once the mines are destroyed, civilians move in to dig up the plants.

Troops have had to wipe out coca plants manually since last year when President Juan Manuel Santos ended a two-decade-old aerial eradication program over health concerns signaled in a World Health Organization-sponsored report reclassifying the chemical herbicide glyphosate as a carcinogen.

But amid rising cocaine production, Colombia is being forced to rethink its anti-drug strategy again, taking into account the possibility of a more stable future now that the government has reached a cease-fire deal with rebels that will take effect once a final accord is signed, probably in the coming weeks.

If and when that happens, the military is hopeful it will be able to shift its energy and resources from fighting rebels to pursuing top drug traffickers.

In the meantime, Defense Minister Luis Carlos Villegas insists that Colombia's military is not easing up on eradication, as was suggested in June in Senate testimony by the State Department's top anti-narcotics official.

"We haven't renounced the war on drugs," Villegas said in an interview. "Nobody in the world has produced more dead, more blood, or more resources than Colombia."

As proof, he points out the government's scaling up of manual eradication to replace the now-grounded crop duster plans that were piloted by Americans. In the coming months, Colombia will quadruple to around 200 the number of eradication crews, each comprised of about two dozen civilians escorted by a much-larger security detail of sharpshooters, paramedics and land mine removal teams.

It's dangerous work. In the last 15 years, 153 people on manual eradication teams have been killed, the majority from exploding land mines or booby traps, according to the anti-narcotics police. More than 500 have lost limbs or suffered serious injuries.

It's also costly and slow-going: On an average day, each crew can only clear about a hectare (about 2½ acres). That's why the government has managed to eradicate only about 9,000 hectares (22,000 acres) of coca fields this year compared to the 172,000 hectares (425,000 acres annually at the height of the fumigation program a decade ago.

With some people warning that Colombia will soon be awash in coca because the manual eradication process moves so slowly, Santos earlier this year decided to bring back pesticides on a more limited — and what he says is safer — basis.

Starting later this year, crews will be equipped with hazardous materials suits and motor-powered sprayers worn on their backs, allowing them to spread a glyphosate substitute over longer distances.

But even those committed to the program's success recognize its limitations and yearn for a return to the days of fumigation.

"Without a doubt the results aren't going to be sufficient," Capt. Manuel Perez, a police special forces instructor, said between loud blasts at Los Pijaos training base, a drive of a few hours south of Bogota.

Elsewhere on the sprawling base, in an experimental field growing 23 varieties of coca, procedures and equipment are being tested against growers' ever-changing techniques. The biggest concern lately is a strain called "Boliviana negra" — Black Bolivian, also known as "Supercoca," which is found in the southern jungles and being studied for its resistance to the herbicide.

However strong the government's eradication effort, the new strategy's linchpin is the FARC. The group has long funded its insurgency by levying a "war tax" on cocaine shipments moving through areas it controls. But as part of peace talks, it has already agreed to abandon the business and join the government in an alternative development program to wean an estimated 64,000 mostly-peasant families off the drug trade. Although details are scarce, the two sides in July made public a pilot project in western Antioquia state near where they're already removing land mines together.

Conservative critics of Santos see his plan as tailor-made to appease the rebels, who have long compared the fumigation with glyphosate to the U.S. military's use of the defoliant Agent Orange during the Vietnam war.

Experts say FARC members are taking advantage of the relative safety provided by the end of fumigation, as well as the long build-up to a peace deal, to urge farmers to increase coca production so they will be well-positioned to receive government assistance when hostilities cease.

Meanwhile, the coca growers have little faith the government can deliver. A visit earlier this year by The Associated Press to a FARC-controlled area in Antioquia found some coca growers bracing for confrontation and showing no sign of slowing down.

"We'll fight whoever comes and touches our plants," said Fernando Zapata, head of a community council in the tiny hamlet of San Isidro, his hands swollen green from so many years stripping coca leaves from its knobby bush. "We're organized and will fight to the death if necessary. They want to stop us from feeding our families."

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Associated Press writer Cesar Garcia in Bogota contributed to this report. Jacobo G. Garcia also contributed.

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Joshua Goodman is on Twitter: https://twitter.com/apjoshgoodman. His work can be found at http://bigstory.ap.org/journalist/joshua-goodman.