According to the realist perspective, how does anarchy in the international system lead to war?

What will be an ideal response?

Varies. Anarchy, or the decentralized distribution of power in the international system, means that there is no “world 911,” and states must therefore rely on themselves for their own security (which is known as self-help). In this situation, war is always possible because there is nothing to effectively prevent it. Realists argue that other features of the international system make war more or less likely, although they disagree on specifics. Realists disagree on whether the system is most prone to war when there is a single dominant power or when there is equilibrium. Even if they agree that war is less likely under equilibrium, realists disagree on whether bipolar systems (systems with two great powers) or multipolar systems (systems with several great powers) are less prone to war. In addition, there are several specific ways in which self-help can lead to war. One way is through the security dilemma, a situation that arises when a state arms to make itself more secure but threatens other states by doing so. Another is through the balance of power, which occurs when states form alliances (and possibly go to war) to prevent a single state from dominating the international system. Some realists argue that war is most likely when power transition occurs—that is, when a dominant power declines relative to rising powers.