<p>The Russia-Ukraine situation has become a notable international issue, with the resulting changes in global diplomatic relations gaining considerable attention. To examine the evolving diplomatic strategies of the countries involved, the authors apply the theories and methodologies of complex network games. First, the authors incorporate overflow payoff theory from economic and trade cooperation networks to summarise the spillover income phenomenon in diplomatic games and to facilitate modelling. Drawing on the classic Fermi rule in network game theory, the authors introduce belief and the same-strategy factors to propose an evolutionary game rule driven by interests, beliefs, and neighbouring strategies. Using numerical simulations, the authors examine the factors that affect the evolutionarily stable strategies of various nations. The authors also conduct comparative experiments to validate the scientific credibility of the method proposed in this paper.</p>