<p>Trade conflicts have become a major disruption to global supply chains, yet existing studies mainly focus on decentralized settings and provide limited insight into how a focal firm reconfigures a centralized supply chain under tariffs and export restrictions. This paper develops an optimization model for global supply chain configuration (SCC) of a centralized platform-product supply chain. Methodologically, the contribution lies in operations research modeling: we extend the guaranteed-service SCC framework by jointly incorporating tariff propagation along cross-border flows, option-dependent international logistics, quality-dependent demand, and development costs for substitute components under export restrictions. Using a mobile phone supply chain as an industrial case, we conduct a scenario-based computational analysis under alternative trade-policy environments. The results show that (i) tariff escalation pushes inventory away from downstream market-facing nodes toward upstream stages, with stronger upstream transfer in the downstream-cost-intensive (DCI) supply chain than in the upstream-cost-intensive (UCI) supply chain; (ii) geographic reconfiguration depends critically on the size of the tariff-affected market: small markets support a home-centered configuration, whereas larger markets induce a stronger shift toward locations near or within the tariff-affected country; (iii) when tariffs are combined with export restrictions, the supply chain becomes more regionalized, and final product quality depends strongly on substitute development cost.</p>