Mustafa and his son, Ekin, are among the seasoned smugglers who have made numerous nighttime crossings over the mountainous Turkish-Iranian border to procure petrol in Iran for resale in Turkey. On one recent trip, father and son loaded empty jerry cans on either side of four horses, and then took to the hills along the frontier, where they would wait for the right moment to make their move into Iran.

On this particular occasion, they were a little more nervous than usual. Only two nights before, two teenage brothers had tried to evade border guards and the $3-per-horse bribes that many smugglers pay in the hope of securing a "safer" passage. Spotted, border guards opened fire on the brothers, killing one and leaving the other in a local hospital with a shattered leg. Mustafa recounted that the same brothers had been shot and wounded in 2008.

The news gave all smugglers reason to pause. But smugglers along this stretch of the frontier tend to be the type who quickly set aside their fears. That is because the potential profits from their activities -- typically amounting to about $60 per horse per trip -- represent a relative fortune in an area that is intimately acquainted with poverty.

In admitting his fear about making a trip so close to the shooting incident, Ekin said the tension when crossing the border was routinely intense. "Guys who smoke, do not smoke when we get close to the border," he said.

Once across the border and in Iran, Turkish smugglers meet up with Iranian contacts and quickly do their deals. Modern technology abets the illicit trade, as most fuel purchases are arranged in advance via text messages and mobile phone calls. Iranian contacts also help arrange the return trip, with bribes once again serving as a sort of travel insurance. Still, no amount of bribe-offering can completely eliminate the possibility of arrest, or coming into the crosshairs of a border guard's rifle.

This trade is viable due to the differential between Turkish fuel costs, which are at standard European Union levels, and the subsidized petrol and diesel costs in Iran. There is little petrol refining performed within Iran, so it is mostly purchased from aboard and is in turn discounted by up to 80 percent for consumer sale. This high level of subsidization allows for a generous profit for those who smuggle it into Turkey.

If all goes well on any given procurement mission, the smuggled fuel is quickly transported from local villages to larger population centers using trucks with additional hidden tanks. In some cases, drivers may fill up cars with large tanks then head for the nearest city, where much of the tank's contents is siphoned and sold, leaving the driver with just enough left to make the return trip to his home village. Once the smuggled petrol is unloaded in cities and large towns, it is sold at illegal street-side stalls on backstreets, or even from secret pumps within garages.

This phase of the smuggling operation also has its hazards, underscored by the existence of a fenced-off lot on the outskirts of Van, the largest city in the area, where row after row of confiscated cars and trucks sit. The vehicles were evidently seized on account of their alleged involvement in smuggling operations.