Prime Minister Boris Johnson has allowed Huawei to play a major role in Britain's 5G network.
This means the Chinese technology giant will be involved in the roll-out of the country's communications upgrade.
However, the decision could cause trans-Atlantic tension, after the White House warned Mr Johnson away from adopting Huawei over security fears.
The US has blacklisted Huawei due to worries that it will act as a backdoor for the Chinese state to get access to western nation's data.
What has the UK said?
Huawei has been branded a "high risk vendor".
However, it will still be allowed to play a peripheral role in the UK’s 5G network.
Guidance from the National Cyber Security Centre states that high risk vendors should be excluded from all safety-related and safety-critical networks in critical national infrastructure and from sensitive geographic locations, such as nuclear sites and military bases
Huawei will also be limited to a minority presence of no more than 35% in the periphery of the network, known as the access network, which connects devices and equipment to mobile phone masts.
What is Huawei?
Chinese technology giant Huawei is the world’s second-biggest smartphone manufacturer and one of the world’s biggest suppliers of telecommunications equipment.
It says it is a private company “wholly owned” by its employees, but questions have been raised about the mechanics of its ownership structure.
It was founded in 1987 by Ren Zhengfei, who, before his career in industry, worked in the engineering branch of the People’s Liberation Army.
What is 5G?
The implementation of 5G is expected to bring with it download speeds 10 times faster than what 4G currently offers.
Huawei has invested billions of pounds into research and development around 5G network infrastructure and, as a result, is now considered the industry leader in 5G technology.
It is also already part of the existing network infrastructure in a number of countries, including in the UK.
As a result, using one of Huawei’s rivals, and most likely alternatives – Ericsson or Nokia – for the building of 5G networks, is likely to cause a delay and add cost to the introduction of widespread 5G in the UK.
In contrast, none of the four largest mobile carriers in the United States use Huawei equipment in their networks.
What allegations has the US made against Huawei?
US President Donald Trump's administration has blacklisted Huawei, calling the company "a national security concern".
Indeed, the company has come under scrutiny over allegations of close ties to the Chinese state.
Founder Mr Zhengfei’s past links to the military have been cited as a concern, as has China’s history of state sponsorship and surveillance.
Chinese law can also compel firms to co-operate with Chinese national intelligence work, which some critics have suggested could see Beijing require Huawei to spy on people through so-called “back doors” in its telecoms equipment.
Huawei has vehemently denied the allegations of any ties with the Chinese state and says it abides by the laws of every country in which it operates.
What has the US said to the UK about Huawei?
US Secretary of State Mike Pompeo has directly urged the UK not to use Huawei.
Mr Pompeo, who is due to visit the UK later in the week, said: “The UK has a momentous decision ahead on 5G.
“British MP Tom Tugendhat gets it right: ‘The truth is that only nations able to protect their data will be sovereign’.”
He retweeted a comment by Mr Tugendhat, chairman of the Commons Foreign Affairs Committee in the last parliament, in which the MP said: “The real costs will come later if we get this wrong and allow Huawei to run 5G.”
What has Huawei said?
Huawei has always denied having ties to the Chinese government, with the company’s founder denying that Beijing has ever asked his company to help spy on its clients.
Mr Zhengfei, in an interview last year, said: “I love my country. I support the Communist Party. But I will not do anything to harm the world.”
He said Huawei had never been asked to share “improper information” about its partners by the government.
“I personally would never harm the interest of my customers, and me and my company would not answer to such requests.
“No law in China requires any company to install mandatory back doors.”
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