Concerns about internal security have risen since September 11 and many countries are considering how to tighten migration and asylum rules to screen out potential terrorists. But the idea of immigrants or refugees as an internal security threat is not new. It is a worry that has been steadily growing for a decade, in response to another security problem: the exponential increase in migrant trafficking and smuggling networks. The central problem here is not so much who enters, but rather how they enter. Trafficking is not only highly dangerous and exploitative for those trying to move, but it also poses a clear security threat. So how serious is this, and why has it emerged now?