WASHINGTON, March 22 (Xinhua) -- Despite strong warnings from business groups and trade experts, U.S. President Donald Trump on Thursday signed a memorandum that could impose tariffs on up to 60 billion U.S. dollars of imports from China, the latest unilateral move that poses a threat to global trade.

Trump has directed U.S. Trade Representative Robert Lighthizer to publish a list of proposed Chinese goods that could be subject to tariffs in 15 days, while the U.S. Treasury Department will have 60 days to propose restrictions on Chinese investment in the United States, according to the presidential memorandum.

The tariffs "could be about 60 billion" dollars, Trump said Thursday at the White House before signing the memorandum. But a senior White House official told reporters earlier in the day that the number would be close to 50 billion dollars.

The memorandum comes after strong warnings from Chinese and U.S. business groups in recent weeks.

China will "take all necessary measures" to defend its rights and interests, an official with the Ministry of Commerce said Thursday, responding to media reports that Washington will soon release results of a Section 301 investigation against China.

"China has made clear its position several times that it stands firmly against such unilateral and trade protectionist practices from the U.S. side," the official said.

In a letter to Trump on Sunday, 45 U.S. trade associations, representing retail, technology, agriculture and other consumer-product industries, urged the administration not to move forward its tariff plan on Chinese imports, as it would hurt U.S. consumers and companies.

A group of 25 major U.S. retail companies, including Walmart, Costco and Best Buy, also warned on Monday that any additional broad-based tariff would worsen U.S. inequity and "punish American working families" with higher prices on household basics like clothing, shoes and electronics.