(AP) – No international letters, no international packages: A top official with a 192-country postal union says that’s what Americans can expect if the Trump administration goes through with plans to pull of an international postal treaty over concerns about China.

Pascal Clivaz, deputy director-general of the Switzerland-based Universal Postal Union, says the agency reached out quickly to U.S. officials after receiving a letter from U.S. Secretary of State Mike Pompeo this week announcing Washington’s plan to pull out of the union in a year if the treaty isn’t renegotiated.

The U.S. says it’s willing to renegotiate. But the threat is the latest sign of U.S. President Donald Trump’s go-it-alone approach to many issues, from the environment to trade to the Iran nuclear deal.

“It will have dramatic consequences for American consumers. It will cost them enormously. They will be all alone against all the countries of the world,” Clivaz told The Associated Press on Friday. “They won’t even be able to send (a package) to a neighboring country. It’s an accord that links everybody.”

Word of the planned pullout is the latest facet of Washington’s multi-level trade dispute with Beijing.

The U.S. administration says the treaty allows China to ship packages to the U.S. at discounted rates at the expense of American businesses.

Clivaz acknowledged the U.S. concerns about China were at the root of the problem, but said agreements within the UPU since 2016 have moved toward “improving the issue with China.”

“It’s not at the level that Mr. Trump and others want it, but we’re close. So we want to continue negotiating,” he said.

The U.S National Association of Manufacturers has applauded the planned U.S. move, calling the postal pact “outdated” in the age of e-commerce and at a time of Chinese manufacturing dominance.

A U.S. pullout from the 144-year-old organization, a specialized U.N. agency, would strip the U.S. from access to special codes needed to send and receive mail internationally, Clivaz said. Any U.S. companies that need them – like FedEx or UPS – would lose access too, he said.

“This agreement regulates all the issues: technical problems, customs issues, security issues. Without the codes, without this green light, you can’t move a single letter or package,” he said.

“The next step is in their court: to give us a meeting,” Clivaz said of the U.S. government.

Renegotiation of the treaty would require a majority vote among UPU members.