"Relevant negotiations and agreements should not target or harm the interests of third parties," said a Chinese spokeswoman.

A 20% tariff will be placed on Vietnamese exports to the US, with a 40% levy on any goods deemed to be transshipped through the country, Trump said in a social-media post on Wednesday.

Trump’s move to reduce the tariff for Vietnam comes just ahead of a July 9 target, when he is projected to increase duties on most imports. More than a dozen countries are now scurrying to negotiate analogous agreements with the U.S. to evade high tariffs.