Donald Trump has declared a “national emergency” which will give the US government sweeping powers to prevent American companies doing business with foreign suppliers of telecommunications equipment including Huawei.
Mr Trump signed an executive order which accused foreign powers of targeting US technology, and industrial espionage.
It cleared the way to ban Huawei from America’s 5G networks.
The US has repeatedly claimed that Huawei’s equipment could be used for spying by China.
Mr Trump had already barred the US government from use of Huawei equipment, but has now extended that to all US companies.
Mr Trump’s commerce secretary will be able to stop deals involving equipment built by a foreign power when there is an “unacceptable risk to US security or public services.
Sarah Sanders, the White House press secretary, said: “The president has made it clear that this administration will do what it takes to keep America safe and prosperous.
“We will protect America from foreign adversaries who are actively and increasingly creating and exploiting vulnerabilities in information and communications technology infrastructure and services in the United States.”
The US has threatened to withhold intelligence from Britain if it allows Chinese technology giant Huawei to help build its 5G network.
Robert Strayer, deputy assistant secretary for cyber at the US state department, said last month America will be forced to “reassess” its intelligence-sharing relationship with the UK.
He warned that the Chinese state could order Huawei to “undermine network security, to skim personal information, distribute cyber attacks and disrupt critical infrastructure”.
The Telegraph published details of Mrs May’s decision to allow Huawei to bid for 5G contracts last month. A week later, Gavin Williamson was sacked as defence secretary after being accused by Mrs May of leaking the decision.