United Kingdom exports of aluminium to the U.S. are tiny, but in March the UK's Aluminium Federation said it feared the 10% tariffs.
European Commission President Jean Claude Juncker said Trump's tariffs were "totally unacceptable" and promised to retaliate in due course. Unilateral responses and threats over trade war will solve nothing of the serious imbalances in the world trade.
Prior to Ross's announcement, a senior Canadian official, speaking on condition of anonymity citing the sensitivity of the situation, confirmed Canada has prepared a list of USA products that might face retaliatory tariffs, but declined to give further details.
By contrast, US producers are restarting previously idled operations and investing in new ones amid a period of "record confidence", said John Tumazos, a New Jersey based steel industry analyst. Growing trade tensions have clouded a benign outlook for the global economy, which is on track to grow at its fastest pace in seven years this year and next, according to the International Monetary Fund.
In March, Trump imposed a 25% tariff on steel imports and a 10% tariff on aluminium, but granted temporary exemptions to the EU, Canada, Mexico, Brazil, Australia and Argentina. "We are awaiting their reaction".
European officials had assumed that Trump would follow through with duties on their exports (negotiations over the Iran deal having already convinced them that trying to dissuade the US president from scoring diplomatic own-goals was a futile enterprise).
The shares of American steel producers, which have supported the tariffs, rose across the board on Thursday. "This is a very strong Canadian action in response to a very bad US decision". He reiterated the US concerns over the indirect flow of cheap Chinese steel into the USA through other countries.
But she says they could hit Canadian businesses, some of which say they are watching closely to see how the dispute unfolds.
Fears of a trade war between the US and its allies are buoyed by the fact that US President Donald Trump is also seeking to levy German auto makers; the tariffs would be similar to those on steel and aluminum.
Trump's legal authority for imposing the tariffs rests on the claim that America's reliance on foreign steel is a threat to its national security.
Liam Fox questioned the United States decision to 25% tax on steel and a 10% tax on aluminium from the EU, Mexico and Canada.
US trading partners had demanded that the exemptions be extended or made permanent.
And President Donald Trump has the authority to alter the tariffs or impose quotas or "do anything he wishes at any point" - allowing "potential flexibility" to resolve the issue.
The impact of tariff threats is being felt in the US too, given the amount of steel Canada exports south of the border and the large quantity of other goods purchased from various states.
"The Section 232 steel and aluminum tariffs have already had major, positive effects on steel and aluminum workers and jobs and will continue to do so long into the future".
Meanwhile, the White House also announced it may also introduce new tariffs on Chinese imports as well as restrictions on intellectual property - a move that would make good on promises President Trump made during his campaign.
He said trade talks with the European Union had also been fruitless.
"We will consider whatever actions they do take but our focus is as mentioned on national security aspects of steel and aluminum", he said. The action was mainly targeted at China over accusations of flooding the global market with cut-rate metals and dragging down prices. But Canada and Mexico were reportedly stunned by the move.
In contrast to France, Germany - Europe's largest economy - has taken a milder tone since March, seeking to be a peacemaker in the negotiations, downplaying talk of retaliation and seeking to keep both sides talking.