Around the world, nefarious state and nonstate actors are extracting enormous value from forests to fund their operations. The unlawful clearing of land and the harvest, transport, purchase, and sale of timber and related commodities have long been dismissed as a niche concern of environmental activists. But this is a mistake. Although unsustainable deforestation imperils the environment, illegal logging also poses an outsize—and underacknowledged—geopolitical threat. Environmental crime constitutes a growing economic and national security threat to the United States and countries around the world. Yet Washington has largely ignored illegal logging’s role in its fight against transnational criminal organizations, drug cartels, terrorists, and rogue regimes, as well as China’s part in this illicit trade. Thankfully, the blueprint for fighting transnational crime already exists: better cooperation among governments, increased enforcement, more transparent supply chains, public-private partnerships, and most important, following the money.