Concerns over allowing Huawei access to UK 5G networks are set to be raised during next week’s presidential visit.
US national security adviser John Bolton confirmed the issue, which led directly to the sacking of former defence secretary Gavin Williamson, would be discussed when President Donald Trump makes his state visit.
Although the UK Government insists no decision has yet been taken, leaked reports from the National Security Council suggested Prime Minister Theresa May could allow the firm access to peripheral but not core parts of the network.
Speaking at the American embassy in London, Mr Bolton said Huawei posed “a different kind of threat” and the US would accept “zero” risk of telecommunication networks being intercepted by foreign powers.
Suggesting he expected the UK Government to take a harder stance against Huawei, he said: “I’m not sure this decision that’s reached prime ministerial level in final form… These are the sorts of things you can’t resolve in one meeting.
“The discussions continue – I’ve been in conversation with (civil service chief) Mark Sedwill about this frequently – and I’m sure they will go on.
“This is not some philosophical disagreement, this is trying to understand the nature of the technology, trying to understand the nature of the threat, how if at all it can be mitigated against.”
When asked directly if the issue would be raised again next week, he said “probably so, yeah”.
Mr Bolton made it clear that the US did not accept there could be a distinction made between peripheral and core access to the system, saying a “key difference” to earlier generations of the technology was that 5G “is not so easily divisible into core elements and peripheral elements”.
He said: “It’s one thing with a different technology to say you can accept a higher level of risk in peripheral elements as long as you control and protect the core elements.
“In fifth generation, one of the reasons it’s faster… is the distinction between core and periphery is much less clear, if you can make it at all.
“So that the threat posed by equipment that’s compromised coming in is much greater and much more difficult to mitigate against.”
Asking whether anybody would be prepared to accept that “a foreign power is reading your mail all the time, at their will”, Mr Bolton said his government was not and listed allies who had also decided the risk was too great.
“When it comes to our government systems, the United States has said zero is the level of risk we will accept,” he said.
“That’s the same answer Australia has given, the same answer New Zealand has given, it’s the same answer a number of other governments have given.
“That’s what we’re trying to explain to all of our partners, that we need to be clear about this being a different kind of threat.”