On Wednesday, Trump administration officials told reporters that they had begun the process of withdrawing from the Universal Postal Union with the goal of making China pay its fair share of shipping costs to the U.S.

Trump is right that the regulations should be reevaluated, but threatening to pull out of the organization or worse, actually doing so, is a bad move.

The first signs of this approach came in August, when Trump issued a memo directing U.S. representatives to renegotiate UPU rules in September and threatening that the U.S. would move to set its own shipping rates if it was not happy with progress made in talks.

Those talks did lead to a proposal, but it would not be presented until 2020, and the administration isn’t waiting around. Instead, Washington has moved to formally withdraw from UPU (which will take a year) and to set up self-declared shipping rates (which will take at least six months).

Here’s what’s wrong with that approach.

The first calls for the UPU came from the U.S. in 1863 to solve a vexing problem: the need to negotiate separate postal treaties with each country and then figure out the postage in the various countries that parcel traveled through and finally to find someone to deliver the package in the destination country. That meant that even mailing a letter would be complicated. For any destination abroad, a separate stamp would be required for each and every country it passed through.

If that sounds like headache, it was.

The U.S. had a solution, and called for the creation of an International Postal Congress. The Royal Prussian Minister for Posts thought it was a good idea and set up the Universal Postal Union, which was officially created in 1874 by the Treaty of Bern. Then, it was known as the “General Postal Union.”

The General Postal Union had three distinct principles: First, it established that a uniform flat rate should be charged to mail a letter anywhere in the world; second, that postal authorities had to treat foreign and domestic mail equally; and third, that each country could keep the money it collected for international postage.

When the United Nations was founded in the aftermath of World War II, the Universal Postal Union became part of the new international organization in 1948. Since then, the UPU has changed its rules to meet changing international demands.

In 1969, the UPU changed its payment system to implement terminal dues or a system of fees that were payable between countries based on the difference in the total weight of mail between them. In 1991, the application of these fees to periodicals was modified. The U.S. subsequently negotiated separate terminal dues with 13 European countries and Canada.

In short, the UPU solved an important problem and, as demonstrated by prior shifts in regulations and independent agreements with other countries, can be modified to meet demands of changing shipping markets and the needs of individual countries.

Today, the UPU is again facing new problems: a rapid increase in e-commerce as well as huge shipping volumes from countries like China. The UPU has worked to fix some of these issues with new rules for bulky letters and small packages, but problems still remain.

For the Trump administration, the main issue is with the UPU classification system that ranks countries based on their level of development and determines what rates are charged for packages under 4.4 pounds. Countries listed at high levels of development pay extra to help boost development elsewhere, while those listed as developing get a break. At first blush, that might seem fair, because the classification lists China as a developing country despite its rapidly-growing economy. This has led to U.S. consumers, and the U.S. Postal Service itself, subsidizing China's rise as a manufacturing powerhouse at the expense of American businesses that must pay full price for shipping.

That's right: In 2018, it costs more to ship an item within the U.S. than between China and the U.S. That undercuts U.S. producers and means that the U.S. picks up part of the tab for shipping items made elsewhere. That difference costs the U.S. about $300 million each year.

But as demonstrated by revisions in UPU policies, there is a better solution — to change the classifications and regulations. Although Trump has repeatedly favored bully tactics in negotiations, that approach has accomplished little that wouldn’t have been accomplished otherwise, and it has soured relationships with key allies and the international community.

Moreover, by threatening the organization, Trump is making the same mistake that he did with the ongoing trade war against China. He has underestimated the high political costs to other leaders of appearing to be bullied by the U.S., which at times makes agreements and resolutions more difficult.

That could pave the way for the U.S. to follow through on its threat to just leave the organization outright, which would have disastrous consequences.

Negotiating postal treaties with individual countries would make international shipping much more costly and complicated for U.S. producers and consumers. That would be a blow to U.S. commerce, business, and consumers who rely on global trade and the norms of international shipping.

Moreover, by withdrawing from the organization instead of working to reform it, the U.S. would miss a key opportunity to pressure China to reform with the support and backing of allies — rather than going it alone. Indeed, by pulling out, the U.S. would cede substantial power to China in the international body. Trump and lawmakers backing this effort need to realize that the U.S. will lose far more than it gains in doing so.