Signaling a sharp departure from a decades-long US-led drive for more open and less regulated trade, Trump declared that America had been "ravaged by aggressive foreign trade practices".
Japanese Foreign Minister Taro Kono said the tariffs "could make a significant impact on the economic and cooperative relationship between Japan and the US, who are allies".
Lighthizer was expected to be in Brussels this weekend for meetings with European and Japanese trade officials. Argentina made a similar case.
The WTO has been reluctant to rule against that argument.
Leaning on a little-used and decades-old national security clause in United States trade law, Trump said he was fulfilling a campaign promise.
Malmstrom told reporters the European Union was ready to complain to the World Trade Organization, and retaliate within 90 days. "Their excess capacity alone exceeds the total US steel-making capacity". "The steel capital of the United States should be in America, with American mills and American workers".
In fact, the entire American steel industry has been losing money since 2009, until prices rose past year in anticipation of further tariffs.
But there was political criticism aplenty, especially from Trump's own Republican Party.More news: Waiting game: Browns still not sure of Joe Thomas' future
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Yet at no time has there been a suggestion that close allies Canada and Mexico constitute any kind of security risk to the U.S.
EU Trade Commissioner Cecilia Malmstrom tweeted after Trump's announcement that "the EU should be excluded from these measures".
While China does not directly export much steel to the United States, it is the world's largest steel producer and has been widely blamed for causing a glut of steel on world markets.
Beijing vowed to "firmly defend its legitimate rights and interests".
"The biggest priority as a Congressman representing New Mexico is ensuring our local businesses are not adversely impacted by what the finalized package of tariffs includes and how it is applied", Pearce said. Therefore, Senate Finance Chairman Orrin Hatch voiced that the ultimate takers of the punishment will be both the American firm and individual, who purchases the steel and aluminum products. It was the most explicit threat yet from the country in the escalating trade row.
If the American tariffs are put in place, Malmström said, the European Union could take three steps: take the case to the WTO; add safeguards to protect the European Union against steel diverted from the United States or impose tariffs on a series of American-made goods. Judging from the strong negative reaction coming from all directions, it would seem foolish for the U.S.to follow through on the suggested tariffs, since it would likely result in a lose-lose scenario for both sides. Whether the pursuit of measures to stem imports of steel and aluminum were originally seen as part and parcel of the NAFTA renegotiations or whether this is an opportunistic melding of otherwise completely separate issues is hard to tell.
The WTO's Dispute Settlement Body has never arbitrated a case filed under its national security clause - known as Article 21 - which was first enshrined after World War II in the General Agreement on Tariffs and Trade (GATT).
While carrying a message to Washington to push forward a diplomatic breakthrough over North Korea, South Korea's national security office chief Chung Eui-yong asked US officials to support Seoul's request for a waiver, a presidential spokesman said.