Abstract: Against the backdrop of the global green energy transition, the interaction between resource nationalism in South America’s “Lithium Triangle” and the United States’ “New Monroe Doctrine” is reshaping cross-regional lithium flows and the international division of labor along the lithium value chain. To assess the systemic effects of extreme geopolitical competition on resource allocation in the global lithium battery industry chain, this paper develops a multi-layer trade network covering four stages of the lithium battery industry chain: ore and primary processed products, refined materials, cathode materials, and lithium batteries. A dual-stream temporal graph neural network （Two-Stream Temporal GNN） is used to simulate network topology evolution and cross-layer transmission under a set of geopolitical shock scenarios from 2025 to 2029. The research results suggest that exclusionary geopolitical intervention would redirect South American lithium flows and alter resource access patterns across major demand markets. Yet stronger intervention does not necessarily produce greater gains for allied economies, because it may also constrain total resource supply. The analysis further shows that shocks at the upstream of the chain are amplified as they move across production stages. Specifically, a 28% contraction in South America raw material trade is associated with declines of more than 60% in global trade volume at both the refined material and battery stages, underscoring the extent to which China’s midstream and downstream manufacturing remains dependent on external upstream inputs. Meanwhile, intensified geopolitical competition deepens the mismatch between resource flows and manufacturing capacity. Under this scenario, U.S. imports from South America rise by 52%, while refined material trade links among East Asian economies would shrink by more than 80%. These shifts not only disrupt established patterns of industrial coordination, but also lower the overall efficiency of the global lithium supply chain. Finally, the paper proposes policy responses in three areas: diversifying resource sourcing, strengthening secondary resource recycling, and advancing technological innovation alongside international industrial cooperation.