Britain on Tuesday bowed to growing US pressure and ordered the phased removal of Chinese telecoms giant Huawei from its 5G network despite warnings of retaliation from Beijing.
The policy reversal hands a long-sought victory to US President Donald Trump's administration in its geopolitical tug-of-war with China.
The White House said the decision "reflects a growing international consensus that Huawei and other untrusted vendors pose a threat to national security, as they remain beholden to the Chinese Communist Party".
But the move threatens to further damage Britain's ties with the Asian power and carry a big cost for UK mobile providers that have relied on Huawei equipment for nearly 20 years.
Huawei called it "politicised" and likely to put Britain "in the digital slow lane".
The politically-fraught change in Britain's digital future was made by Prime Minister Boris Johnson during a meeting with his cabinet and National Security Council.
It requires companies to stop buying new 5G equipment from Huawei starting next year and strip out existing gear by the end of 2027.
"This has not been an easy decision, but it is the right one for the UK telecoms networks, for our national security and our economy," digital minister Oliver Dowden told parliament.
Johnson infuriated Trump and upset some members of his own Conservative party by allowing the Chinese leader in global 5G technology to help roll out Britain's speedy new data network in January.
The UK was then completing its tortuous departure from the European Union and looking to establish strong ties with powerful Asian economies that could fulfil Johnson's vision of a "Global Britain".
But the Trump administration told the UK government that its choice imperilled intelligence sharing because British signals could be intercepted or manipulated by China.
Washington believes the private company can also shut down rival countries' 5G networks under Beijing's orders 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 Washington sanctions in May that blocked Huawei's access to US chips at the heart of 5G networks.
The sanctions did not impact older 3G and 4G providers and Britain left its guidance for those networks unchanged.
Johnson had come under intensifying pressure to not only dump Huawei but also adopt a tough line with China for its treatment of Hong Kong and repression of ethnic Uighurs in the western Xinjiang region.
But he also pledged to voters last year to bring broadband access to all Britons by 2025.
British telecoms companies had lobbied strongly against the policy reversal because of the cost of taking existing equipment out and finding untested alternatives.
Dowden conceded Britons will now have to wait longer to get full access to the speedy new network.
"This means a cumulative delay to 5G roll-out of two to three years and costs of up to £2 billion ($2.5 billion, 2.2 billion euros)," he said.
"This will have real consequences for the connections on which all our constituents rely."
But officials insisted that Huawei had managed to install only a "small amount" of equipment since the 5G system began being offered to UK consumers last year.
Johnson has challenged the Trump administration to come up with a reliable and cost-effective alternative to the Chinese firm.
Britain is pushing for the creation of a 5G club of nations that can pool their resources and provide individual components for an alternative solution that could be applied across the world.
The UK government said the process would begin with South Korea's Samsung and Japan's NEC -- two veterans with broad production capabilities -- while offering protection for Finland's Nokia and Sweden's Ericsson to ensure they remained viable players in the field.
Ericsson's regional head Arun Bansal said his firm was "ready to work with the UK operators to meet their timetable, with no disruption to customers".
Nokia's chief executive for UK and Ireland, Cormac Whelan, said the firm also has "the capacity and expertise to replace all of the Huawei equipment in the UK's networks at scale and speed".
But UK officials caution that all existing players have some Huawei equipment in their supply chains that needs to be taken into account.