Chess mostly boils down to a mathematical optimization problem within a fixed, predetermined rulset, with predefined success and failure conditions.
Geopolitical decisions involve pursuing outcomes in situations involving far more variables, often changing in realtime due to factors outside the "game board", where the rules are complex, mutable, and not necessarily known in advance, and where the success and failure conditions are subjective and may themselves change during the course of the scenario.
Geopolitical situations are Chess, Nomic, and Werewolf all rolled into one. How good is AI at winning all of these games?