<p>Russia and Ukraine are critical global wheat producers and exporters, and the Russia-Ukraine conflict is affecting global food security, the magnitude and outcome of its impact remain uncertain. To provide insights, we constructed an international wheat trade network based on the complex network theory and improved the under-load cascading failure model by incorporating trade preferences and national response strategies. By simulating the effects of halted wheat exports from Russia and Ukraine on wheat supplies during each round of cascading transmission, we analysed the propagation of supply shocks and identified vulnerable regions and key alternative exporters during the cascading process. We established a network resilience index to assess the impact on the wheat trade network and conducted a sensitivity analysis of network resilience under different Russian and Ukrainian export scenarios to identify the factors that determine resilience. We found that all regions within the global wheat trade network were affected by supply shocks under cascading effects. China, India, the United Kingdom, and the United States can serve as alternative sources after Russia and Ukraine halt their wheat trade, whereas Indonesia, Lebanon, Libya, Malaysia, and Tunisia are likely to halt exports due to an inability to meet minimum domestic consumption under multiple scenarios. Our results indicate that vulnerable countries, particularly low- and middle-income nations in Asia, Africa, and the Middle East, should enhance interregional wheat trade connectivity, prioritize diversifying their wheat import sources, establish emergency grain reserves, and enhance domestic self-sufficiency to better cope with future supply shocks.</p>