Britain on Tuesday ordered its telecom providers to stop purchasing 5G equipment from China's Huawei giant from the start of next year, and to strip out all of its equipment by 2027.
"From the end of this year, telecoms providers must not buy any 5G equipment from Huawei," digital minister Oliver Dowden told parliament after Prime Minister Boris Johnson chaired meetings with his cabinet and the National Security Council.
In response, Huawei said Britain's "disappointing" decision was "bad news for anyone in the UK with a mobile phone" and threatened to put the country into the digital slow lane.
It also urged the government to reconsider.
"We remain confident that the new U.S. restrictions would not have affected the resilience or security of the products we supply to the UK," a spokesman said.
Last week, China warned Britain it could face repercussions in terms of its international reputation as a trading nation if it backed down on Huawei.
Johnson infuriated U.S. President Donald Trump and upset some members of his own Conservative party by allowing the Chinese 5G leader to help roll out Britain's speedy new data network in January.
The U.K. was then completing its tortured departure from the European Union and looking to establish strong ties with powerful Asian economies that could fulfill Johnson's vision of a "global Britain."
But the Trump administration told Johnson's government that its decision imperiled intelligence sharing and could even result in the Pentagon relocating some fighter jets from its English base.
Washington believes the private Chinese company could either spy for Beijing or shut down rival countries' 5G networks in times of war.
Huawei has always denied this and pointed to two decades of cooperation with British security agencies that checked on the safety of its existing 3G and 4G networks.
The British review was triggered by new U.S. sanctions in May that blocked Huawei's access to U.S. chips and semiconductors at the heart of 5G networks.
The restriction raised the possibility of Huawei having to switch from trusted U.S. suppliers to alternatives whose safety could not be guaranteed by U.K. security agencies.