  The severity of war, measured by battle deaths, follows a power-law
distribution. Here, we demonstrate that power law also holds in the temporal
aspects of interstate conflicts. A critical quantity is the inter-conflict
interval (ICI), the interval between the end of a conflict in a dyad and the
start of the subsequent conflict in the same dyad. Using elaborate statistical
tests, we confirmed that the ICI samples compiled from the history of
interstate conflicts from 1816 to 2014 followed a power-law distribution. We
propose an information-theoretic model to account for the power-law properties
of ICIs. The model predicts that a series of ICIs in each dyad is independently
generated from an identical power-law distribution. This was confirmed by
statistical examination of the autocorrelation of the ICI series. Our findings
help us understand the nature of wars between normal states, the significance
of which has increased since the Russian invasion of Ukraine in 2022.
