it's clear why the dirt-poor former Soviet Central Asian republic of Tajikistan is on the verge of becoming a narco-state.After the U.S.-led invasion of Afghanistan in 2001, the United States and other Western powers looked the other way as opium and heroin production surged to record levels, making Afghanistan by far the world's biggest producer.Much of the ballooning supply of drugs shipped across Afghanistan's northern border, up to one-fifth of the country's output, has traveled to and through Tajikistan. The opium and heroin funded rampant corruption in Tajikistan and turned the country, still hobbled by five years of civil war in the 1990s, into what at times seems like one big drug-trafficking organization.Every day last year — extrapolating from United Nations estimates — an average of more than 4 metric tons of opium, which can be made into some 1,320 pounds of heroin, moved on the northern route. Put another way, the equivalent of nearly 6 million doses of pure heroin — at 100 milligrams each — is carried across the northern Afghan border each day.