The US is disappointed by the UK's decision to press ahead with using Chinese telecommunications firm Huawei in its 5G network, an American official said.
The Government has granted Huawei a limited role in its 5G mobile network, despite US warnings about the impact this could have on intelligence sharing.
A senior Trump administration official said: "There is no safe option for untrusted vendors to control any part of a 5G network.
"We look forward to working with the UK on a way forward that results in the exclusion of untrusted vendor components from 5G networks."
Sharing an article about the Government decision on Huawei, Democratic US Senator Chris Murphy tweeted: "America has never been weaker. We have never had less influence.
"Not even our closest ally Britain, with a Trump soulmate in Downing Street, listens to us anymore."
Huawei can only provide parts for 35 per cent of the total network and will not be allowed to control the technology's roll out entirely in any city.
The company is also to be excluded from safety-critical networks in critical infrastructure and from the network in sensitive locations.
But America has long opposed the company having even a small part in the network, saying promises by UK spy chiefs that it won't give the Chinese government some access are naive.
The company has consistently denied having an intelligence sharing relationship with the government in Beijing.
Digital Secretary Baroness Nicky Morgan said: “We want world-class connectivity as soon as possible but this must not be at the expense of our national security.
"High risk vendors never have been and never will be in our most sensitive networks.
“The government has reviewed the supply chain for telecoms networks and concluded today it is necessary to have tight restrictions on the presence of high risk vendors.
“This is a UK-specific solution for UK-specific reasons and the decision deals with the challenges we face right now.
“It not only paves the way for secure and resilient networks, with our sovereignty over data protected, but it also builds on our strategy to develop a diversity of suppliers.
“We can now move forward and seize the huge opportunities of 21st century technology.”
