World stocks fell as worries about harsh US steel and aluminum tariffs hit global financial markets. US stocks finished solidly lower, with the Dow Jones Industrial Average losing 1 percent and the S&P 500 shedding around 0.7 percent. Key European markets also fell, while Asian equities opened lower on Friday. It comes after US Commerce Secretary Wilbur Ross announced that a 25 percent tariff on steel imports and 10 percent tariff on aluminum imports will be imposed on the EU, Canada and Mexico from 4 GMT on Friday. Our White House correspondent Nathan King, has the latest.

Making America great again is a lot like America going it alone these days. As of Friday, steel and aluminum tariffs will have been imposed on its neighbors Canada and Mexico, its biggest allies in the European Union, Japan, and its single biggest trading partner, China. A necessary approach, says the U.S. commerce secretary, to address a global problem.

WILBUR ROSS US COMMERCE SECRETARY "Well there's overproduction of steel and there is over-capacity throughout the world. And so we have needed to deal with it in a very global manner. You can't just deal with dealing with the one country."

Washington's trading partners object on the grounds that this violates World Trade Organization protocols. The U.S. has justified its unilateral actions, using a Cold War-era law written to protect U.S. national security, not specific American industries.

The effects are already being felt. Steel prices have been rising in global markets and the uncertainty is roiling global stock markets. The U.S. commerce secretary, however, is downplaying the economic consequences.

WILBUR ROSS US COMMERCE SECRETARY "Well, even if the E.U. does retaliate and even if some others do, it still will remain unlikely to be as much as one percent on our economy."

NATHAN KING WHITE HOUSE "U.S. Commerce Secretary Ross is calm, but there are many U.S. industry leaders who are not. They've expressed concerns that retaliation by this country's largest trading partners may hit industries that have nothing to do with steel or aluminum. Potentially, doing more harm than good to the U.S. economy. Nathan King, CGTN. the White House."