Violent non-state actor
A violent non-state actor (VNSA) is an organization that uses illegal violence (i.e. force not officially approved of by the state) to reach its goals. The term has been used in several papers published by the United States military.
Thomas, Kiser and Casebeer (2005) assert that "VNSA play a prominent, often destabilizing role in nearly every humanitarian and political crisis faced by the international community".
As a new species of actors in international relations, VNSAs represent a departure from the traditional Westphalian sovereignty system of states in two ways: by providing an alternative to state governance and challenging the state's monopoly of violence. Phil Williams, in an overview article, states that "violent non-state actors (VNSAs) have become a pervasive challenge to nation-states" in the 21st century".
Williams argues that VNSAs develop out of poor state governance but also contribute to further undermining governance by the state. He explains that when weak states are "unable to create or maintain the loyalty and allegiance of their populations", "individuals and groups typically revert to or develop alternative patterns of affiliation". This causes the family, tribe, clan etc. to become "the main reference points for political action, often in opposition to the state".
According to Williams, Globalization has "challenged individual state capacity to manage economic affairs, it has also provided facilitators and force multipliers for VNSAs". Transnational flows of arms, for example, are no longer under the exclusive surveillance of states. With the onset of globalization, development of transnational social capital and alliances, and funding opportunities for VNSAs have all flourished. ".
Williams identifies various types of VNSAs:
Criminal organizations and gangs are essentially illegal business organizations. ("Crime for them is simply a continuation of business by other means".) 
Researchers at the Overseas Development Institute propose that engagement with VNSAs—which they call armed non-state actors—is essential to humanitarian efforts in conflicts, as it is often necessary for facilitating access to those affected and for providing humanitarian assistance. However, humanitarian agencies too often fail to engage strategically with VNSAs. This tendency has strengthened since the end of the Cold War, partly due to the strong discouragement of humanitarian engagement with VNSAs included in counter-terrorist legislation and donor funding restrictions. In their opinion further study is necessary to identify ways in which humanitarian agencies can develop productive dialogue with VNSAs.
- Bartolomei, Jason; Casebeer, William; Thomas, Troy (November 2004). "Modeling Violent Non-State Actors: A Summary of Concepts and Methods". IITA Research Publication, Information Series (Colorado: Institute for Information Technology Applications, United States Air Force Academy) (4).
- Casebeer, William, (USAF, USAF Academy); Thomas, Maj. Troy (USAF 1st Fighter Wing IN.) (December 2002). "Deterring Violent Non-State Actors in the New Millenium". Strategic Insights I (10):[page needed]. Archived from the original on March 6, 2008.
- Jackson, A (2012). "Briefing Paper: Talking to the other side: Humanitarian engagement with armed non-state actors". Overseas Development Institute.
- Thomas, Troy S.; Casebeer, William D. (March 2004). "Violent Non-State Actors: Countering Dynamic Systems". Strategic Insights III (3).
- Shultz, Richard H.; Farah, Douglas; Lochard, Itamara V. (September 2004). "Armed Groups: A Tier-One Security Priority". INSS Occasional Paper (USAF Institute for National Security Studies, USAF Academy) (57).
- Thomas, Troy S.; Kiser, Stephen D.; Casebeer, William D. (August 2005). Warlords Rising: Confronting Violent Non-state Actors. Lexington Books. ISBN 978-0-7391-1190-1.
- Williams, Phil (28 November 2008). "Violent Non-State Actors". Zurich: International Relations and Security Network.
- Mulaj, Klejda (2010). Violent Non-State Actors in World Politics. London: C Hurst & Co. ISBN 9781849040174.
- Thomas, Troy S.; Kiser, Stephen D. (May 2002). "Lords of the Silk Route: Violent Non-State Actors in Central Asia". INSS Occasional Paper 43. USAF Institute for National Security Studies USAF Academy, Colorado.