International alliance is a system of military and political relationships between states. It is a key element of global power politics, and it allows states to pursue complex grand strategies. It is difficult, if not impossible – certainly in the modern world – for a single state to seek global, or even regional, primacy on its own. Such a quest is usually enabled by an intricate network of partnerships, as was the case in the Cold War coalitions or in more ancient times, when the Indian strategist Kautilya (reigned c. 321–c. 297 bce) advocated the art of “the enemy of one’s enemy being one’s friend.”
As alliances multiply, their benefits may also become problematic. They do not come for free and they often require sacrifices of domestic interests. They can also become dangerous if countries rely too heavily on alliance-derived gains and develop dangerous habits. This is why alliance policy needs to be constantly reevaluated and re-calibrated.
Another potential problem is that alliances can encourage devolutionary movements by empowering local groups that feel disconnected from central governments or want greater autonomy. This can result in a widening of regional identity and the emergence of new territorial disputes among alliance members. It is also possible that alliances may be harmed by the behavior of individual members, such as when some alliance partners play a double game or are tempted to pursue their own geopolitical interests at the expense of their shared commitments.