Massive US tariffs on EU steel imports came into force on Friday as Britain made it clear a trans-Atlantic trade war would be bad for both sides.
The 25% levy on steel was branded "patently absurd" by International Trade Secretary Liam Fox.
Dr Fox dismissed American claims the tariff, along with a 10% levy on aluminium, was needed for national security reasons as he signalled the UK was prepared for "tit-for-tat" action.
Branding the move by US president Donald Trump as "just protectionism", he said: "We absolutely do not rule out counter measures.
"Obviously, we still hope the United States will think again about this.
"But, it would be a great pity if we ended up in a tit-for-tat trade dispute with our closest allies."
Labour's shadow international trade secretary Barry Gardiner said the US move risked a global trade war.
He said: "Liam Fox needs to take urgent action to defend British industry from these unfair measures.
"If the Government had any doubt as to how 'special' our relationship with the US is to President Trump then these tariffs make it clear that even close allies will not be spared from his America First policies.
"Labour would coordinate a decisive set of counter-measures with the EU and challenge the USA at the World Trade Organisation."
The EU is set to take action against the US at the World Trade Organisation, while imposing duties on American imports expected to include orange juice, peanut butter and other goods.
Dr Fox said he would speak to US commerce secretary Wilbur Ross about the situation again on Monday.
Welsh Secretary Alun Cairns spoke to the First Minister of Wales, Carwyn Jones, about the tariffs, saying the Government was seeking a solution.
A Government spokesman said: "The Secretary of State gave assurances that the UK Government is fully committed to reaching a successful resolution.
"Both ministers agreed to work together and be a strong voice for Welsh steel as discussions progress."