US President Donald Trump sought to ratchet up pressure on China for trade concessions by proposing a higher 25 percent tariff on $200 billion worth of Chinese imports, his administration said on Wednesday.

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

“The increase in the possible rate of the additional duty is intended to provide the administration with additional options to encourage China to change its harmful policies and behavior and adopt policies that will lead to fairer markets and prosperity for all of our citizens,” Lighthizer said in a statement.

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

Reuters reported that two trump administration officials told reporters on a conference call that Trump remains open to communications with Beijing and that through informal conversations the two countries are discussing whether a “fruitful negotiation” is possible.” We don’t have anything to announce today about a specific event, or a specific round of discussions, but communication remains open and we are trying to figure out whether the conditions present themselves for a specific engagement between the two sides,” one of the officials said.

But the move drew swift condemnation from U.S. business lobby groups worried that tit-for-tat tariffs would start to hamper economic growth.

“Escalating tariffs against China is the wrong approach to address legitimate concerns U.S. businesses have with China’s harmful practices,” said Myron Brilliant, head of international affairs for the U.S. Chamber of Commerce.

China, which has accused the United States of bullying, again vowed to retaliate if Trump proceeds with the measures, warning that pressure tactics would fail.

“US pressure and blackmail won’t have an effect. If the United States takes further escalatory steps, China will inevitably take countermeasures and we will resolutely protect our legitimate rights,” Chinese Foreign Ministry spokesman Geng Shuang told a regular news briefing.