Donald Trump has threatened to launch a new trade war against Britain.The President warned he would slap 100 per cent tariffs on imports to the US on any country that imposes a tax on tech giants.And he said it would come into force immediately, overriding any existing deals he has done.It could mean fresh economic pain for the UK, which already has a Digital Services Tax.The two per cent levy on the revenues of foreign social media and search engine firms was introduced in 2020 and raised £944million in 2025-26.If President Trump goes through with his threat it could mean the end of the 10 per cent tariff rate he agreed for most UK goods last year.He wrote on his Truth Social platform on Friday: 'Numerous European Countries have been discussing the imminent implementation of a Digital Services Tax on American Companies. 'Some of these Countries are close to actually doing this. Donald Trump has threatened to launch a new trade war against Britain'Please let this statement serve to represent that any Country that imposes such a Tax will immediately be met with a 100% TARIFF on any and all Goods sent to the United States of America.'This TARIFF will supersede Trade Deals made with the Country, whether implemented, signed, or not. 'Additionally, the 100% TARIFF will be immediately imposed, if they proceed.'It echoes a threat he made specifically to the UK earlier this year.He told reporters at the White House in April: 'We've been looking at it and we can meet that very easily by just putting a big tariff on the UK, so they better be careful.'If they don't drop the tax, we'll probably put a big tariff on the UK.'His warning could also spell trouble for Andy Burnham, who has proposed increasing business rates on online retailers such as Amazon in order to cut taxes for pubs and clubs.On Friday night, Shadow Business Secretary Andrew Griffith said: 'This is further evidence that Labour have seriously damaged our relationship with the US.'Labour - both Keir Starmer and his likely successor Andy Burnham - must urgently work with our US partners to try to avoid such damaging tariffs on British firms already struggling with this Government's tax hikes.'Tariffs have become the US president's weapon of choice in seeking to compel American adversaries and allies alike to meet his strategic and economic demands. He has issued a number of threats against the UK - but generally the country has come off better than some of its European counterparts. Earlier this year, Mr Trump vowed to implement increasing tariffs on the UK and other European allies until the US is allowed to purchase Greenland from Denmark.He also threatened last year to impose new tariffs and export controls on countries with digital taxes or regulations affecting American tech giants.In a post on Truth Social from August 2025, Mr Trump said he would 'stand up to countries that attack our incredible American Tech Companies'.'Digital Taxes, Digital Services Legislation, and Digital Markets Regulations are all designed to harm, or discriminate against, American Technology,' he wrote.'This must end,' he said and vowed that 'unless these discriminatory actions are removed', he would 'impose substantial additional tariffs' on the offending nation's exports to the US.Meanwhile in August last year, Mr Trump quietly brought in tariffs on hundreds of goods that contain steel or aluminium.The items affected included washing machines, garden furniture, fire extinguishers, and parts of a child's cot or highchair.Triumph Motorcycles, Britain's largest manufacturer of motorbikes, was among those caught by surprise by the move.Nick Bloor, the chief executive, said at the time: 'The recent announcement by the US Commerce Department has come as a surprise, especially given the recently negotiated trade agreements.'JCB chief executive Graeme Macdonald said the expanded tariffs would hit all 30,000 of the diggers and construction machines it exports to America each year.He said: 'The tariffs as they now stand are hugely punitive and they catch every machine we ship to the US. It will make us have to reconsider how we trade with North America.'Mr Trump's latest tariff threat adds wider strains in UK-US relations, which have deteriorated since Sir Keir Starmer ruled out British involvement in the Iran war.Earlier this year, Mr Trump suggested the terms of the UK-US trade agreement brokered last year 'can always be changed' in an interview with Sky News.Downing Street declined to comment.