Among the few points of agreement between Donald Trump and his detractors is that the first 73 days of his second term have changed the world. In February and March he inflicted what may prove to be fatal blows against the Western alliance that has protected much of the developed world for nearly 80 years. Yesterday—“Liberation Day”, as Mr Trump sees it—he made an unprovoked attack on global trade. In our opinion, it was “Ruination Day”. Our leader explains why this is “the most profound, harmful and unnecessary economic error in the modern era” and how other countries can lessen the damage. We also analyse Mr Trump’s tariffs in detail and assess the toll they are taking on financial markets worldwide.