The United States has filed a formal complaint with the World Trade Organization against China, alleging theft of U-S intellectual property. The expected move is part of President Donald Trump's package of trade measures. China's Ambassador to the W-T-O says Beijing will challenge the complaint. China is digging in its heels on trade. At the W-T-O, as many as 40 members spoke-out against Trump's tariffs on steel and aluminum, as they took effect. CGTN's Roee Ruttenberg reports on some of the day's other developments in this growing confrontation.

On Friday, as US tariffs on imports of steel and aluminum went in effect, President Donald Trump announced: yet another country may be exempt.

DONALD TRUMP US PRESIDENT "We have a lot of good news to report. Some tremendous trade deals are being made with various countries. we're negotiating very long, very hard, but very quickly, and the deal with South Korea is, according to (US Commerce) Secretary Ross and (US Trade Representative) Bob Lighthizer, is very close to being finished."

Lighthizer, the US Trade Representative, and his boss, Wilbur Ross, the US Commerce Secretary, have been negotiating the exemptions.

WILBUR ROSS US COMMERCE SECRETARY "We believe we are relatively close to a pretty comprehensive resolution with the South Korean government. It would encompass, if it goes through, both the 232s and broader trade issues, and we hope by sometime next week to be able to have a real announcement."

Section 232 of the half-century old Trade Expansion Act is what allows Trump to impose tariffs based on national security. Indeed, that's what he cited earlier this month, as he signed off on duties of 25% on imports of steels and 10% on aluminum. Many countries -- including China -- complained. And many -- except China -- have been exempt.

Critics see it as part of a series of moves by the Trump administration targeting Beijing.

On Thursday - in a separate move under Section 301 of the Trade Act - the White House announced $60 billion worth on tariffs specifically aimed at Chinese goods. Beijing protested. As did the head of the World Trade Organization. Roberto Azevedo warned of the consequences of Washington's bypassing the international body set-up to resolve such disputes. On Friday, the US submitted its official complaint in Geneva. 

There were also warnings - and consequences -- stateside.

Markets went into a tail-spin. FedEx - a global shipper based in the US - tumbled to a five year low. Some are bracing for more.

MAX BAUCUS FORMER US AMBASSADOR TO CHINA "President Xi's part - and all the years I was over there, you kept hearing it - he cares about party legitimacy, standing power, and that means a stable economy so he's going to retaliate as much as he can but not too much in a way that might damage the Chinese economy.

ROEE RUTTENBERG WASHINGTON DC "Observers in the US sense that so far, the reaction from China has been in response to the 232 -- the steel and aluminum tariffs. They expect reaction to the 301 tariffs - signed off this week -- to be much bigger. And they're closing watch Beijing's moves. Roee Ruttenberg, CGTN, in Washington."