The outbreak of a new war in the Middle East, together with a destructive tariff war, makes for a lethal combination in a sluggish world economy. Notwithstanding the possibility of a tentative ceasefire, the odds of imminent global recession have increased sharply.

One shock was bad enough. US President Donald Trump’s tariffs, wherever they eventually settle, imply downside risks to global growth. But the potential for a second shock – a war between Israel and Iran that has now ensnared the United States – compounds the problems for an increasingly vulnerable world economy. It ...