In the face of Afghanistan's unprecedented boom in opium production, neighbouring Iran is trying to batten down its border to slow down smuggling, building moats, walls and other large-scale projects.
Iran spent more than US$26 million last year alone on the border projects, which also include large embankments, new border posts and lengths of barbed wire along parts of its 2,000-kilometre border with Afghanistan and Pakistan.
"The transit of narcotics is a complicated issue. Smugglers are wealthy. They change tactics and use modern equipment that makes it more and more difficult to discover. We need new, modern equipment to combat drugs effectively," General Ali Moayedi, Iran's anti-narcotics police chief, said during a recent tour of the border.
Neighbouring Afghanistan is the main source of drugs coming into Iran and heading to Europe and the US.
Last year, 209,000 hectares of poppies were planted across Afghanistan, up 36 per cent over the year before. They produced an estimated 5,500 tonnes of opium, according to the United Nations drug agency. By comparison, only a little over 7,000 hectares of poppy field were eradicated.
This year's harvest is expected to match or even exceed last year's record. In coming years, opium will grab an even larger share of Afghanistan's already troubled economy, as money from US military contracts and aid work dries up. The UN estimates that some 200,000 families in Afghanistan are involved in opium production and that the country has some one million addicts.
As a share of Afghanistan's economy, opium looms large: the UN estimates the potential gross value of Afghan opiates last year was around US$3 billion - equal to 15 per cent of the country's gross domestic product.
"In 2013, we confiscated 573 tonnes of various kinds of narcotics from drug smugglers, showing a 14 per cent increase compared to 2012," Ali Reza Jazini, a senior Iranian counternarcotics official, told foreign diplomats on the tour.
General Mohammad Kazem Taqavi, the local border police chief, said his forces clashed with armed drug smugglers the day before the tour.
"Some 50kg of narcotics were seized, one of the smugglers was killed and their weapons and equipment were confiscated," he said.
The UN has provided special equipment to Iran to detect drugs hidden in tight and closed spaces such as a vehicle's fuel tank.
Taqavi said more equipment was needed, along with more international help.