West Africa, a region that has barely begun to heal from a decade of civil wars, is once again under attack. The new threat grows silently, like a cancer, and the international community appears powerless to respond. An international network led by Latin American drug cartels and the Lebanese Islamist group Hezbollah has chosen West Africa, among the poorest and more corrupted corners of the world, as the nexus for illegal trade in cocaine, oil, counterfeit medicines, pirated music and human trafficking. International law enforcement officials say the profits fuel terrorist activities worldwide. The past three years has seen a staggering increase in drug trafficking in particular, making West Africa — and especially the countries of Guinea Bissau, Nigeria, Ghana and Guinea — the premier narcotics region of Africa. The consequences are most visible in Guinea Bissau, which saw the double assassination of its president and army chief on the same day in early March and more recently the murder of two leading politicians in the struggle for succession. The consequences stretch as well to the slums of Bissau, where crack-fueled prostitution is driving a new AIDS epidemic in a region where even basic health care is beyond the reach of many — and where young people turning to the drug trade become the unwitting soldiers of organized crime. What’s happening in Guinea-Bissau, Africa’s first narco-state, is a red flag of warning for the region — and for the world.