UK Prime Minister Boris Johnson defied the Trump administration and granted permission to the Chinese telecoms company Huawei to help develop Britain's 5G network.
The UK government said in a written statement on Tuesday that it would give Huawei a major role in building the country's 5G network, despite warnings about potential threats to security.
But the UK's Department for Culture, Media, and Sport said Huawei would be excluded from the network's "core" functions, operating just 35% of the overall network.
The company will also be excluded from operating "sensitive" parts of the UK's communications network, "such as nuclear sites and military bases."
"We want world-class connectivity as soon as possible but this must not be at the expense of our national security," Digital Secretary Baroness Morgan said. "High risk vendors never have been and never will be in our most sensitive networks."