Using the MIRAGE-Power model, this Working Paper simulates a trade war initiated in 2025 by the new US administration. The central scenario consists in a 60 percentage point tariff increase on all US imports from China, a 10 percentage point tariff increase on all products from other partners, except Canada and Mexico, and reciprocal tariff retaliation. World GDP and world trade decrease respectively by 0.5% and 3.4% in volume, with significant losses for the US and China, and gains for Canada and Mexico. A substantial reallocation of bilateral goods trade flows is taking place at global level. Additional scenarios show that: details of the tariff reform matter; the discriminatory tariff treatment of China benefits other trading partners; trade retaliation increases US economic losses; if Non-Tariff Measures are included in this trade war, the consequences are worse; if Canada and Mexico are included in the trade war, both experience significant losses in terms of GDP and trade. Last, the paper shows that the US will not be able to replace the federal income tax with tariff revenues, even with a revenue-maximizing tariff. Antoine Bouët, Leysa Maty Sall, Yu Zheng