By Vanessa Buschschluter
BBC News, Villavicencio, Colombia
Production is down in the world's biggest cocaine-producing country. Ten years ago, Colombia churned out almost 1,000 tonnes of cocaine annually, now it is down to less than 300 tonnes.
"It's still one of our country's biggest problems," says Col Jose Angel Mendoza, deputy head of the Colombian anti-narcotics police force. "But we're on the right track."
However, success has brought its own problems, the colonel says. "A couple of years ago you'd find a 30-hectare (74-acre) coca field and you'd use a plane to spray it with herbicides.
"Now, the coca fields are much smaller, hidden in dense jungle and hard to access. Often, the plants have been booby-trapped, and the surrounding area is mined, making it risky to eradicate them by hand."
The enemy, too, has changed, Col Mendoza says. The big drugs cartels have been broken up, smaller criminal gangs which are harder to target have taken their place.
And after the capture and death of many of the top leaders of the Farc, Colombia's main rebel group is also becoming more fragmented, making it in some ways harder to fight.
So, the battle goes on. Dressed in combat gear and armed with M4 rifles, the anti-narcotic force's 7,200 agents look more like soldiers than police officers.
They even have their own 600-strong special operations force, the Jungla, or jungle squad.
Sgt Alfredo Nino is one of them. Soft-spoken and a little shy, he seems an unlikely candidate for an elite fighting force.
Sitting next to his wife in their neat home in Villavicencio, 55 miles (90 km) south of Bogota, he talks about his decision to join the police at the age of 18.
Sgt Nino's wife Liliana supported his decision to join the special ops force
"No-one in my family had been in the security forces, so I don't know why it grabbed me. I just saw an ad and it looked like a good career path," he said.
The initial training took him far from home. He adapted well, he insists, but the first time his father came to visit, he wanted to leave with him and rejoin the family. "But the guards stopped me."
But he soon took a liking to the work of the special operations team.
He joined Copes, a police group specialising in urban combat. A natural sharpshooter, he became an instructor teaching others to shoot, among them his future wife, Liliana Martinez.
When they got married, he joined her squad in Villavicencio, which provided police escorts for politicians. Three years ago, Liliana left the force to look after their two children, aged 12 and six.
After a while as a bodyguard, Sgt Nino volunteered for the Jungla.
Sgt Nino carries a pistol at all times
"Our mission is to combat the drugs trade, and we're trained to fight and survive in the most inhospitable areas of the country for days, weeks, months, whatever it takes," he said.
Liliana backed his decision but found the three years he spent with the Jungla tough for the family.
"He'd call me in the morning from Bogota, and a couple of hours later he could be at the other end of the country, deployed on some highly dangerous mission," she said.
Sgt Nino says it was a privilege to be a Jungla. "You know your colleagues are as well trained as you are and you are always on the frontline of the battle."
But the missions could be relentless and there were times when he didn't come home for six months. "When I finally did return and wanted to embrace my 18-month old daughter, she didn't recognise me and ran away crying," he recalls.
That's when he decided something needed to change, and he asked for a transfer from the Jungla to an anti-narcotics group in Villavicencio.
Sitting in his windowless office at police HQ filing fuel expenses, Sgt Nino still wears combat gear, and always has a Beretta pistol strapped to his thigh. "I always carry a gun," he says, "you never know whom you may have crossed in my line of work."
He has no regrets about taking on a job with more administrative duties. "I have spent nine years at the sharp end of the war, I've done my bit, now I'm taking it easy for the sake of my children," he says.
Then his eyes light up: "But when there is a raid, I'm the first one to be called. Once a jungla, always a jungla!"
When the call comes, Sgt Nino puts on his flak jacket and helmet, picks up a rifle and leads his team into another raid on a cocaine lab in the jungle or a drug bust in the city.
And it is not just drugs they are looking for. These days, the unit seizes arms and ammunition too.
Network of informants
While I am with them, they get a tip-off about a suspected Farc rebel hiding in a local hotel.
They believe he could be an explosives expert and are keen to catch him, as an increasing number of their colleagues are being maimed and killed by bombs planted by the Farc to protect their illicit coca crops.
The suspect is apprehended with two illegally held weapons and Farc propaganda material, but no explosives.
It could be enough for a sentence of one to two years, but not quite the coup they had been hoping for.
Is it worth the risks they take, I ask the men conducting the raid. Nationwide, the anti-narcotics police force may have arrested 60,000 people last year but are they not just replaced by new people keen to profit from the lucrative drugs trade?
"It's not a job, it's a vocation!" they insist.
And Col Mendoza is convinced his force is making serious inroads. They are building up a network of informants, both paid and unpaid, which is helping them target even the smallest dealers.
But money is always short, the colonel say, and with US financial support for the war on drugs gradually being cut back, Colombian taxpayers are increasingly having to foot the bill.
I ask him if there is one thing which could tip the balance in this protracted conflict.
The answer is: helicopters.
"We could inflict much more damage," he says," if we had three times as many helicopters to take my men to the ever more remote frontline of the drugs war."