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The US Post Service announced on Tuesday that it had temporarily stopped accepting packages from China and Hong Kong, hours after an order from President Trump came into force that ended duty -free handling of many of these packages.

The United States imports about three million packages a day with a little customs inspection and no tasks collected – with most of them coming from China. An executive order, such as Mr. Trump signed on Saturday, required each package that started on Tuesday morning to contain detailed information about the content and customs code that is valid, as well as payment of these duties.

The provision on low value parcels, known as the minimis rule, was included in a wider order of Mr. Trump, who imposed an extra 10 percent duty on all imports from China.

But low-value packages from China, previously duty-free, now face not only 10 percent duties, but also the many complex tariffs on each category of goods that these shipments have previously skirt completely.

A spokeswoman for the US Post Service did not answer a question of whether the stop was related to the change in the trade rules, but said only that the service would be temporarily suspended on incoming packages from China and Hong Kong so far.

Customs and border protection did not immediately respond to a comment request. The White House did not immediately make comments.

Trump’s executive order imposed a 10 percent duty on all Chinese imports starting Tuesday. The administration also ended the minimis rule for China and argued that the trade provision had become a cord for fentanyl to be brought into the United States.

Trump administration and other critics of the minimis claimed that drugs and precursors used to make them could more easily be sent to the United States using the trade provision as exporters using the minimis do not have to give as much information to US customs and border protection as they would otherwise.

The rapid roll -out of Mr. Trump’s trade orders left some time for post and customs officials to prepare to investigate so many packages. Trump said on January 22 that he would set customs duties in Canada and Mexico on February 1st and then added China to the list on January 23. He signed the executive orders on February 1 to take effect only three days later.

Supporters of the minimis have long said that the elimination of the provision would increase the burden of US customs officials. US customs and border protection is also the primary agency responsible for implementing large parts of Trump’s enforcement measures at the border.

In an online event in October, Ralph Carter, Vice President of Legislative Affairs in FedEx, observed that resources were stretched for US customs officials and that a change to the minimis rules could lead to bottlenecks for senders.

“If we convert these millions of shipments from the minimis to formal, informal approvals, we will have the serious security chain backups because there is simply no resources to control it,” he said. “And then it will affect all importers, not just importers of the minimis.”

FedEx and UPS move a large part of the minimis packages running frequent cargo flights from China to the United States to carry them. None of the companies have yet answered questions about how they will handle the new rules.

Shein and Temu are two of the largest e-commerce companies connecting low costs Chinese factories to millions of US households. Shein refused to comment on the new rules on small packages on Tuesday, while Temu has not yet answered questions sent on Monday.

The rapid expansion of e-commerce has set a dilemma for the United States Customs Eagan, Customs and Border Protection. Customs officials already began to be overwhelmed by small e-commerce packages in 2016, when they persuaded Congress and the Obama administration to raise the minimum value of customs inspection and customs collection to $ 800, from $ 200.

Raising the duty -free minimum has enabled millions of US households to buy very low cost goods from China. But American manufacturers in sectors such as textiles and clothing have claimed that the import of small packages has undermined their ability to remain in business.

The number of duty -free packages has risen ten times since 2016. Congress has discussed the past year how to change the rule of duty -free packages. Mr. Trump has claimed that allowing so many packages in the United States with little or no inspection has created a cord for fentanyl, a synthetic opioid and related supplies to enter the United States.

Jordyn Holman contributed with reporting from New York.