If ARM becomes a US subsidiary of a US company, it falls under the Cfius [Committee on Foreign Investment in the United States] regulations, Mr Hauser told BBC Radio 4's Today programme. That means that if hundreds of UK companies that incorporate ARM's technology in their products, want to sell it, and export it to anywhere in the world including China - which is a major market - the decision on whether they will be allowed to export it will be made in the White House and not in Downing Street. He added that he believed the pledge to retain and increase the number of UK jobs was meaningless unless UK ministers stepped in to make it legally enforceable. But ARM's chief executive played down the threat of export bans. It isn't to do with the ownership of the company, it's all to do with analysis of the product itself, Simon Segars told the BBC. The majority of our products are designed in the UK or outside the US, and the majority of our products don't fall under much of the US export control set of rules. Mr Huang added that ARM had some of the finest computer scientists in the world in Cambridge and he intended to both retain them and attract others to what would become Nvidia's largest site in Europe. The UK prime minister's spokesman said ministers have spoken to both companies, adding that the government would be scrutinising the deal including what it means for the Cambridge HQ. ARM creates computer chip designs that others then customise to their own ends. It also develops instruction sets, which define how software controls processors. It is based in Cambridge but also has offices across the world, including a joint venture in Shenzhen, China. Hundreds of companies license its innovations including Apple, Samsung, Huawei and Qualcomm. To date, ARM says 180 billion chips have been made based on its solutions. When Softbank acquired ARM, it promised to keep the company's headquarters in the UK and to increase the number of local jobs, which it did. Softbank's founder Masayoshi Son described the firm as being a crystal ball that would help him predict where tech was heading. But losses on other investments, including the office rental company WeWork, prompted a rethink. California-headquartered Nvidia overtook Intel to become the world's most valuable chipmaker in July.