Two features have been consistent in the Middle East and North Africa since the era of independence: ongoing violence of all types-and the absence of a collective security structure, which could tackle this violence. Since the end of World War II, the region has seen multiple attempts to organize collective and cooperative security, all of which failed. Since the so-called Arab Spring, movement has come again into regional security. From joint exercises and combat operations to an attempt to create a joint Arab force, the trend seems to be going toward more collective action in the region. As this study shows, however, challenges remain on the way to a true collective defense or security body; issues of sovereignty and distrust will have to be overcome before Arab states can truly move beyond mere alliances and integrate their forces. A successful Arab security system needs to address security in a comprehensive manner. First, it would have to cover security challenges that are not only regional and of interstate nature, but also domestic (such as civil wars). Second, it would have to be able to manage aggression not only from outsiders (such as the attack on Egypt in 1956), but also among member states (such as Iraq and Kuwait). "Internal" here, therefore, has two meanings-internal to the member state, and internal to the alliance. These are both dimensions that a classical alliance (e.g., the North Atlantic Treaty Organization [NATO]) is not concerned with-although any security system seeks the reduction of the possibility of organized violence both within and between states, but preconditions differ. Alliances, or even collective defense systems, will not be enough for the Arab world because they focus solely on the regional aspect of security. Instead, a more holistic system is necessary, which could reduce the likelihood of violence altogether-such as a collective security system, which later could become a security community. The system would have to decide on provisions pertaining to domestic security issues such as unrest or civil war without openly infringing on Arab state sovereignty. When the League's Arab Deterrent Force was sent to Lebanon in 1976, and the Gulf Cooperation Council (GCC) Peninsula Shield was sent to Bahrain in 2011, these moves were possible only because both states had allegedly invited these missions in full sovereignty. There are two main challenges for any type of Arab security architecture to overcome: the first is a highlevel degree of distrust amongst states; the second is that conventional collective security is chiefly concerned with interstate wars-when most Arab conflicts have been either of an intrastate or at least asymmetric nature. Taken together, circumstances for collective security are infinitely more complex than, for instance, those in Western Europe after World War II. Security cooperation requires first and foremost a certain level of trust amongst states participating in any such scheme. After all, suspecting one's ally to threaten one's security defies the idea of any form of cooperation in this field. In the Arab world, however, trust has been porous, because regimes have struggled with issues of legitimacy and sovereignty from the outset. States were born with weak institutions, poor popular legitimacy, and a divided polity. It was not only states that were questioning each other's sovereignty; citizens were questioning regime legitimacy as well. Only in 1964 did the Arab League member states formally put an end to Arab unification efforts, and called on Arab states to cease their propaganda wars and to recognize the principle of non-interference-in practice, many Arab states continued to meddle with the politics within other states. The second challenge is that collective security is generally concerned with interstate conflict and its prevention. To date, there is no comprehensive international system to prevent and settle violent internal conflicts.