When Being A “Friend of a Friend” Keeps the Peace Between Nations

Results suggest that indirect peaceful relationships between nations have a surprisingly strong ability to prevent major conflicts, and that international military alliances may matter more than we typically expect.

Here are many examples of these indirect alliances helping keep the peace. One is the lack of conflict between Turkey and Iran from 1965 to 1979, a period during which they were indirectly connected at two degrees of separation. After losing this connection in 1980, disputes arose between the neighbors, reaching a peak in 1987 when they had a militarized dispute with fatalities.

Many studies have shown that nations with military alliances are less likely to go to war. But this new study is the first to show that neighboring countries without direct alliances are still unlikely to have serious conflicts, as long as they are indirectly connected through an ally in common.

In fact, this peace dividend extends up to three degrees of separation without getting weaker: Nations are much less likely to have wars with their allies, the allies of their allies, and the allies of their allies’ allies.

Funding for the study came from the National Science Foundation and the Alexander von Humboldt Foundation’s Fellowship for Experienced Researchers.