Here’s some free advice for President Trump and his economic advisers, who are frantically searching for measures to ward off a recession: Look in the mirror.

The White House has reason to worry about the economic outlook. There are clear signs of weakness in recent economic data, and forecasters see an increasing chance that the American economy may stop growing for the first time in more than a decade.

The most obvious corrective is to abandon Mr. Trump’s erratic campaign to extract concessions from China and other major trading partners. While there is certainly room to improve the rules of global trade, the Trump administration hasn’t shown it’s up to the task. Lacking any apparent strategy for achieving its goals, it instead is engaged in a campaign of petty vandalism that has unsettled both American businesses and foreign allies.

Tariffs on Chinese imports have come primarily at the expense of American consumers, and Mr. Trump’s trade policies aren’t even helping the intended beneficiaries. He has repeatedly boasted of reviving the steel industry, declaring at a recent rally in Pennsylvania that American steel-making is again “thriving.” But one of the nation’s largest steel makers, U.S. Steel, said this month that it would suspend production at a Michigan plant and temporarily lay off up to 200 workers because of declining prices and demand.