The Book Trailer: http: //www.youtube.com/watch?v=NRcPBck9ky4 The 21st century use of force discourse against terrorism seems to be transforming the limits to the right of self-defense whenever failed states are unable or unwilling to deny safe havens to non-state actors resposible for terrorist acts deemed as an "armed attack." The path to the legitimization of the argument of self-defense against passive terrorism support is traced from a legal perspective. Multiple examples of international jurisprudence and state practice demonstrate a clear shift in use of force discourse within the argument of self-defense against states that harbor international terrorist organizations. This shift leads to a dramatic change in the way sovereignty is appraised, no longer as an unconditional right. State practice discussion regarding the claim of self-defense against passive terrorism support includes recent cases such as U.S.-Pakistan (2011), Turkey-Iraq (2011) and Ethiopia-Eritrea (2012).