Hong Kong’s postal service said on April 16 that it will no longer send packages to the United States, stepping into the escalating trade war between China and the U.S., the New York Times reports.

The de minimis rule that effectively allows packages valued at under $800 to enter the U.S without duties is set to end May 2.

Hongkong Post said it would immediately stop accepting surface postal items containing goods bound for the U.S., and would stop taking airmail packages starting April 27. It said the action was in response to Donald Trump’s tariffs on China, which are now 145%.

“The U.S. is unreasonable, bullying and imposing tariffs abusively,” the postal service said in a statement posted to the Hong Kong government’s website.

The postal service said it would contact senders who posted packages with goods that have not yet been shipped, to return the packages and refund their postage. Documents being shipped to the U.S. would not be affected.

Hong Kong, a former British colony that was promised a degree of autonomy after it was handed over to China, remains a separate customs territory and a free port where goods are exempted from duties. But, during his first term, Trump determined that Hong Kong was “no longer sufficiently autonomous to justify preferential treatment.”