About the best that can be said of the new trade policy emanating from the White House is that it’s all a bluff.

After several days of panic, the U.S. agreed to delay enormous new tariffs on Canada and Mexico in exchange for some token border-security measures.

Yet serious damage has already been done. And these costs will be nothing compared to the harm that the new administration might yet inflict by starting a full-scale global trade war. If that happens, everybody loses — Americans not least. This new economic strategy, if one can dignify it with that term, ranks among the worst White House initiatives ever undertaken.

The logic behind the administration’s trade agenda directly contradicts itself. Start with the executive order threatening to impose tariffs of 25% on Canada and Mexico — in patent violation, by the way, of the free-trade agreement the U.S. championed in 2020. Supposedly, the idea is to force America’s immediate neighbors to stanch the flow of migrants and illegal drugs across their borders.

If the two countries comply (whatever that may mean) and the tariffs remain suspended, they won’t raise any revenue and won’t erect a wall behind which the U.S. manufacturing sector will be revived, defeating the administration’s stated rationale for tariffs in general.

If the real concern is border security, closer cooperation with neighbors is required. Forcing compliance by humiliating countries that wish to be partners is extraordinarily foolish and shortsighted. Which is the better basis for promoting U.S.-led cooperation on this or any other matter — friendship or seething resentment?

If, on the other hand, the goal is to pay for government spending and protect U.S. producers by walling off goods from China, Europe and whomever the administration chooses to bully, the tariff strategy is doomed to fail. The more effective the barriers are in reducing imports, the less revenue they’ll raise (because they’ll shrink the base to which tariffs are applied). The more effective they are in raising revenue, the less domestic producers will benefit (because the flow of imports won’t be much reduced).

Suppose, optimistically, that policy struck a compromise, aiming for a mix of somewhat more tariff revenue combined with a measure of trade protection for U.S. producers. Even then, the idea makes no sense. First, retaliation is certain. Other governments won’t let the White House reduce them to feckless subordinates. The result will be fewer U.S. exports, hence little or no trade-balance benefit.

Second, tariffs will raise prices and cut real incomes. And sheltering U.S. producers from competition will make them less efficient, diminishing growth and living standards while adding to the need for continuing subsidies.

As the familiar cycle of rising protectionism and falling competitiveness escalates, a trade war will yield what it always does: mutually assured stagnation.

It’s possible the threatened tariffs will, in the end, come to nothing. Sooner or later, maybe, deals will be done and any new measures will be rolled back. Of course, the U.S. might help its own cause by doing more to cut off the flow of high-powered guns across the border, as Mexico has requested.

Would that make everything all right? Absolutely not. The administration has already caused real and lasting damage to the U.S.’s economy and to its relations with other countries. How are producers supposed to make plans and invest amid this needless confusion? And what are U.S. allies to make of an administration that views them with such naked contempt? It remains to be seen only whether the harm is manageable and reversible, or something much worse.

Written by the Bloomberg editorial board. Distributed by Tribune Content Agency, LLC.