In many ways, the international system influences the behavior of countries and other actors just as your local system helps determine your behavior. Countries, like you,have free will. In 1991 and again in 2003, the United States could have chosen to remain at peace instead of going to war with Iraq. It did not, though, and a system-level analyst would argue that the U.S. decisions to go to war were reasonably predictable, given the realities of the international system. That system, like your local milieu and every other system, can be analyzed according to four factors: structural characteristics, power relationships, economic realities, and norms.