America’s top diplomat said the Prime Minister had a “momentous decision” ahead of him as he backed criticism of the expected move from a senior Conservative MP.
The US has repeatedly warned Britain not to allow the Chinese telecoms firm – which it accuses of having close links to the country’s government – to run key parts of the high-speed network.
But the UK Government has pushed back, arguing that Huawei has been working with the country’s communications architecture for 15 years and claiming that any security risk can be managed by the National Security Council.
Britain has also accused the US of failing to present an alternative to Huawei, and a decision to give the provider the go-ahead to run so-called “non-core” parts of the network is expected this week.
But Mr Pompeo threw his weight behind Conservative MP Tom Tugendhat, a longstanding critic of the company who is seen as the frontrunner to chair Parliament’s powerful Foreign Affairs Committee.
Mr Tugendhat tweeted: “Sovereignty means control of data as much as land. We need to decide what we’re willing to invest in and who were willing to share our tech with. The real costs will come later if we get this wrong and allow Huawei to run 5G.”
That was endorsed by Mr Pompeo, who shared the message with the comment: “The UK has a momentous decision ahead on 5G. British MP Tom Tugendhat gets it right.”
Justice Secretary Robert Buckland on Sunday night defended the UK’s right to break away from the United States on the issue.
He told the BBC’s Westminster Hour: “The British cabinet has to act in the interest of the United Kingdom first and foremost.
“Of course it will take into account the views of other sovereign states, but as a sovereign state that has to place at the heart of its decision-making national security but also the wider interests of the country, namely the development of broadband, then we’ve got to make a decision calmly and dispassionately on the evidence.”
That view was echoed by the UK’s former national security adviser Lord Ricketts, who said the potential risk to the country’s security was being exaggerated.
“This risk is being blown out of proportion,” the cross bench peer said.
“We already have lots of Huawei equipment on our 4G network which will stay, there is no US or UK 5G technology, so the only others are Ericsson and Nokia, both of whom are also made of Chinese components.
“I’m quite sure, knowing the intelligence community well, that they won’t be recommending to ministers, the course of action that is likely to mess up our intelligence relationship with the US or prejudice UK security.