It is ten times more cost effective to stop narcotics at the source rather than on the street.
In 1978, the U.S. State Department decided it might be a good investment to give the Mexican Government an airplane that could detect the source for heroin as it is being grown. They enlisted technical help from NASA who approached Learjet, since we had been active in the field of photo mapping and remote sensing. While the sale was handled by the government marketing group, I was drafted into assisting on the technical side.
To get a first hand look, we first went to Mexico City to meet with their Attorney General who had just been profiled by Time Magazine for his drug fighting efforts. From there to Culiacan Airport where the AG kept dozens of airplanes they had seized from suspected drug smugglers and hundreds of vehicles (lots of fancy pick up trucks) most of which still had California tags. This was the Mexican's base of operations for their airborne war on drugs.
Everything got sorted out, contracts were signed, the airplane built and modified with a Daedalus multi-spectral scanner, crews were trained and the airplane put into service. The first year, the results were spectacular. From high altitude and at high speed, the aircraft could detect the small fields where the heroin poppies were growing. Ground crews would then be dispatched to destroy the fields. Supplies of heroin dried up, the street price in L.A. soared.
After the first growing season, the U.S. officials went down to Mexico for a project review. The Mexican officials were thrilled but one high level deputy was concerned it was probably to good to be true and kept pressing NASA with questions, can the system be out smarted, will the growers figure out a way to grow poppies that can't be seen by the Learjet?
Reluctantly, the NASA official advised the deputy, the poppy flower pod is lanced before the plant blooms. So the scanner is looking for a particular shade of green. If the grower were to plant something like alfalfa around the poppy plant, it would mask the signature of the poppy plant.
And as you might guess, all of the poppy plant set out the next year and for every year thereafter, were surrounded by alfalfa.