The Observer view on Trump's tariffs: Starmer faces his greatest test as prime minister

The market reaction to Donald Trump's announcement last Wednesday that he would be levying punitive tariffs on imports from the rest of the world was immediate: US stock markets experienced their worst single-day decline since Covid. The long-term implications will depend on how permanent Trump's reshaping of the global economic order turns out to be. At the moment, his administration is sending contradictory signals as to whether these tariffs are here to stay, or whether they are intended to be used to in effect blackmail other countries into doing the bidding of the US. But the global recession they could…