OPEN markets have lowered prices and raised living standards for millions of people but a new tit-for-tat trade war now threatens that progress. After America said on March 8th it would impose 25% tariffs on imported steel, China retaliated with tariffs on dozens of American goods, from pork to wine. America’s president, Donald Trump, and his Chinese counterpart, Xi Jinping, were due to talk on May 8th in an effort to settle some of their differences. Mr Trump, for his part, insists that much of America’s trade with China is “stupid” and is confident that America can win a trade war. Mr Xi, meanwhile, insists that there will be “no winners”.

While Mr Xi is right in thinking that a trade war will leave everyone worse off, the precise impact on American business is more uncertain. Resilinc, a supply-chain analytics firm, has attempted to model the impact of an additional $50bn of proposed Chinese tariffs on American exports ranging from soyabeans to scrap metal.

Using a trove of data covering transactions and inventories for 30,000 manufacturing companies across the world it demonstrates that the losers will not be evenly distributed. Electronics businesses will be least affected. They are reckoned to have the least dependence on China because they do not sell much in the country and have alternative countries to sell to. By contrast, agriculture and aerospace will be most affected: they sell a lot to China and are the least geographically diversified.

When deciding what retaliatory tariffs to impose the Chinese attempt to hurt Mr Trump where he is most vulnerable: in industries that employ his blue-collar supporters. So though America’s president may hope to help 400,000 of America’s metal workers he is simultaneously threatening many more jobs in other industries. At the same time he will be making all consumers worse off by pushing the price of goods up for everyone. No winners indeed.

Read more in “Chain reaction” from this week's edition