Donald Trump’s decision to slap tariffs on steel and aluminium imports was intended to cause quite a stir, and it has. There have been warnings of a 1930s-style trade war from the head of the World Trade Organization, Roberto Azevedo. There have been threats from the European Union that it will retaliate and has US peanut butter and Levi jeans (among other things) in its sights. And it has cost Mr Trump his chief economic adviser, the former Goldman Sachs executive Gary Cohn, who resigned from the White House in protest.

Although he says that trade wars are good and easy to win, Mr Trump is taking bigger risks than he appears to think. If tariffs lead to higher prices for US consumers, the result may be higher inflation and sharper increases in interest rates from the Federal Reserve, America’s central bank. What’s more, the tariff announcement comes at a time when federal tax cuts are set to boost demand in an economy already operating at close to full employment. As imports rise and the US trade deficit widens, Mr Trump will be tempted into further protectionist measures.

If, as seems likely, China is the real target for the president’s action, he is going about things in a typically ham-fisted way, since China is not even one of the top 10 sources of US steel imports. There are better ways of dealing with the global glut of steel that has made life tougher for plants in the US and Europe, but they would involve collaborative action at the Organisation for Economic Co-operation and Development in Paris. Mr Trump is not big on collaborative action.

All that said, talk of a full-blown trade war, let alone a return to the dark days of the 1930s, is wildly overblown. First, steel and aluminium account for only 2% of world trade, so the impact of Mr Trump’s planned tariffs will have only a modest impact. Second, the other big global trade players are – for now at least – likely to be restrained in their response. Both the EU and China are export-led economies and Mr Trump is betting that in any eyeball to eyeball confrontation Brussels and Beijing would blink first. He is probably right about that.

Finally, the state of the world economy is different from the 1930s. Back then, the tit-for-tat protectionism triggered by the imposition of the US Smoot-Hawley tariff in 1930 helped deepen the slump. Today the global economy is growing at its fastest pace since the financial crisis of a decade ago.

Yet Mr Trump’s tariffs are significant for all that. They show that there will be no return to the period between the tearing down of the Berlin Wall and the collapse of Lehman Brothers, when globalisation was in the ascendant. Voters in the US and elsewhere no longer believe that free movement of goods, people and money are guarantors of rising prosperity. Stagnant real incomes, flatlining productivity and hollowed-out communities have taught them that there are costs to outsourcing production to countries that pay scant attention to labour rights and use the state to subsidise cheap exports. Mr Trump has tapped into the sense that trade is part of an economic system that seems configured to favour the rich and powerful. The fact that Mr Cohn was troubled by the president’s tariffs but not by his egregiously pro-rich tax cuts will do little to shake this belief. In an ideal world, trade would be governed by the doctrines of Adam Smith and David Ricardo. International specialisation and comparative advantage would lead to more efficient production, stronger growth and higher living standards. Countries would unilaterally tear down the barriers to trade.

But this is not the way the world actually works. Trade is managed rather than free. Politicians – Mr Trump excepted – talk the language of Smith and Ricardo but act like Alexander Hamilton, whose life has found fame in the hit musical today but is also the original 18th-century architect of US protectionism. Not everybody gains from trade, and some gain a lot more than others. So if there is a trade war Mr Trump will be not the only one to blame. Those who trumpeted the benefits of globalisation said the benefits would be fairly shared. They have not been. They said there would be help for those who lost well-paying jobs. It never arrived.