Rethinking Lean Supply Chain Resilience: A Theoretical Framework for Procurement and Raw Material Sourcing under Trade War Disruptions

Recent years have witnessed an unprecedented rise in geopolitical volatility, with trade wars becoming a sustained and institutionalized form of supply chain disruption. These disruptions directly challenge the foundational assumptions of Lean Supply Chain (LSC) systems, especially the procurement and raw material sourcing stageswhere Just-in-Time (JIT), single sourcing, and zero-inventory strategies are most deeply embedded. While Lean practices have long optimized cost and efficiency, they now face structural vulnerabilities in the face of policy-driven shocks such as tariffs, sanctions, and customs delays. This study aims to explore two core questions. First, it seeks to identify the specific vulnerabilities that have emerged in Lean procurement systems under trade war conditions. Second, it investigates how to construct a theoretical framework that embeds resilience into Lean without compromising its core principles. Thus, this paper proposed a novel system-based framework that maintains the classic InputProcessOutputFeedback logic of Lean procurement, while embedding an Elastic Layer as a cross-functional strategic moderator. This layer introduces adaptive mechanisms such as geo-diversified sourcing, flexible lot-sizing, and resilience-based performance metrics (e.g., Time-to-Recover, Exposure Index). This study reveals that the lean procurement framework integrated with an "elastic layer" can enhance firms structural adaptability to institutional uncertainties such as trade wars, without deviating from core lean principles.