This has now become one of the most important opium- producing centers of the world. Currently, Afghanistan is the second largest producer of illicit opium after Burma. Russian intervention in Afghanistan, followed by prolonged civil war, ravaged the country in many respects, but it created ideal conditions for the cultivation of opium poppies. In the Helmand River Valley, which yields almost 40 percent of Afghanistan's opium crop, resistance leaders defend opium cultivation as an economic necessity after a decade of war and a reduction in outside military support for the mujaheddin. By cultivating opium poppies, rebel leaders and refugees can earn approximately $1,800 per hectare, seven times more than what the wheat cultivation in the same area would yield. In 1988 Afghanistan produced approximately 800 tons of raw opium compared to 130 tons produced in Pakistan. Heroin is still shipped from Iran to the West in large amounts despite the Iranian government's efforts to eradicate such trafficking. A frightening development in drug trafficking in the Golden Crescent is underway. Apparently Colombian drug lords are attempting to forge links with Pakistani and Indian traffickers, who deal with Afghan drugs.