China on Thursday urged the United States to “calm down” after the Trump administration sought to ratchet up pressure for trade concessions by proposing a higher 25-percent tariff on $200 billion worth of Chinese imports.

U.S. Trade Representative Robert Lighthizer said on Wednesday that President Trump directed the increase from a previously proposed 10 percent duty because China has refused to meet U.S. demands and has imposed retaliatory tariffs of U.S. goods.

The higher tariff rate, if adopted, would apply to a list of goods valued at $200 billion identified by the USTR last month as a response to China’s retaliatory tariffs on an initial round of U.S. tariffs on $34 billion worth of Chinese electronic components, machinery, autos and industrial goods.  President Trump has ultimately threatened tariffs on more than $500 billion in Chinese good, covering virtually all U.S. import to China.

The USTR said it will extend a public comment period for the $200 billion list to September 5 from August 30 due to the possible tariff rate increase.

“We hope that those directly involved in the United States’ trade policies can calm down, carefully listen to the voices of U.S. consumers and hear the collective call of the international community,” said Wang Yi, the Chinese government’s top diplomat.  “The United States’ method of adding pressure will not, I’m afraid, have any effect,” Wang Yi told reporters while at a regional forum in Singapore.

Foreign Ministry spokesman Gen Shuang reiterated, at a regular news briefing in Beijing, that the United States’ efforts at “blackmail” would fail.

There has been no formal talks between Washington and Beijing for weeks over President Trump’s demands that China make fundamental changes to its policies on intellectual property, protection, technology transfers, and subsidies for high technology industries.

Two Trump administration officials told reporters that President Trump remains open to communications with Beijing and that through informal conversations the two countries are discussing whether a “fruitful negotiation” is possible.