The US government is about to introduce import tariffs of 25 per cent on steel and 10 per cent on aluminum. Steel and aluminum consuming industries are likely to face higher sourcing costs in the US, with potential impacts on multi-tier supply chains globally. While some countries may be exempted from the tariffs, there is a growing risk of a global trade war. Retaliatory measures from major trading partners including China could cause ripple effects, in particular in the automotive and aerospace industries. This report explores the implications for manufacturing supply chains and potential risk mitigation measures.