WASHINGTON President Trump has taken the first step in imposing tariffs on nearly $50 billion worth of Chinese imports.

The order signed Thursday is aimed at punishing Beijing for stealing American technology and pressuring U.S. companies to hand it over. Trump says the U.S. and China have the largest (trade) deficit of any country in the history of our world and blames that deficit for lost American jobs.

He says the move will make the U.S. a much stronger, much richer nation.

China has already warned that it will take all necessary measures to defend itself, raising the prospect of a trade war between the worlds two biggest economies.

The White House said Thursday that President Trump would direct the Office of the U.S. Trade Representative to publish a list of proposed tariffs for public comment within 15 days. USTR has already identified potential targets: 1,300 product lines worth about $48 billion. The president is also asking Treasury Secretary Steven Mnuchin to come up with a list of restrictions on Chinese investment.

Financial markets skidded Thursday on the risk of growing commercial conflict between the U.S. and China and the possibility that China will impose retaliatory tariffs on U.S. products. Dozens of industry groups sent a letter last weekend to Trump warning that the imposition of sweeping tariffs would trigger a chain reaction of negative consequences for the U.S. economy, provoking retaliation; stifling U.S. agriculture, goods, and services exports, and raising costs for businesses and consumers.

The administration moves on Thursday mark the end of a seven-month U.S. investigation into the hardball tactics China has used to challenge U.S. supremacy in technology, including, the U.S. says, dispatching hackers to steal commercial secrets and demanding that U.S. companies hand over trade secrets in exchange for access to the Chinese market. The administration argues that years of negotiations with China have failed to produce results.