by nations "in order to be either expedient—a rational means toward an accepted end—or moral, the best or least evil course of action". In the same way that people are different in sensing and identifying danger and threats, Wolfers argues that different nations also have different expectations of security. Not only is there a difference between forbearance of threats, but different nations also face different levels of threats because of their unique geographical, economic, ecological, and political environment. Barry Buzan (2000) views the study of international security as more than a study of threats, but also a study of which threats that can be tolerated and which require immediate action. He sees the concept of security as not either power or peace, but something in between. The concept of an international security actor has extended in all directions since the 1990s, from nations to groups, individuals, international systems, NGOs, and local governments. The multi-sum security principle Traditional approaches to international security usually focus on state actors and their military capacities to protect national security. However, over the last decades the definition of security has been extended to cope with the 21st century globalized international community, its rapid technological developments and global threats that emerged from this process. One such comprehensive definition has been proposed by Nayef Al-Rodhan. What he calls the "Multi-sum security principle" is based on the assumption that "in a globalized world, security can no longer be thought of as a zero-sum game involving states alone. Global security, instead, has five dimensions that include human, environmental, national, transnational, and transcultural security, and therefore, global security and the security of any state or culture cannot be achieved without good governance at all levels that guarantees security through justice for all individuals, states, and cultures." Each of these five dimensions refers to a different set of substrates. The first dimension refers to human security, a concept that makes the principle referent object of security the individual, not the state. The second dimension is environmental security and includes issues like climate change, global warming, and access to resources. The third substrate refers to national security, defined as being linked to the state's monopoly over use of force in a given territory and as a substrate of security that emphasizes the military and policing components of security. The fourth component deals with transnational threats such as organized crime, terrorism, and human trafficking.