Whether highly classified missions increasingly should be carried out from countries other than Britain due to confidentiality fears is also being considered, this could see US agents being redeployed.
One former official who only recently left the White House’s National Security Council, which is leading the review, said it was “likely” some assets would be removed from Britain.
“This was not a bluff. You cannot mitigate the danger Boris Johnson is exposing the UK to by letting Huawei into the network,” the source said.
“This is the White House saying, ‘OK, if they’re going to go down this path and put themselves at risk, then how do we protect ourselves?'”
The review marks a significant escalation in the Huawei row, with the US now going beyond words of warning, and taking concrete steps that could end up harming military and intelligence ties.
Council spokesman John Ullyot declined to comment.
The UK has maintained that giving Huawei limited access will not compromise its 5G network.
The review comes as Donald Trump takes an increasingly confrontational approach towards Beijing. The US President has blamed China for not doing more to stop the coronavirus outbreak when it first emerged there.
British Prime Minister Boris Johnson announced in January that Huawei would be allowed to build some of Britain’s 5G network – defying sustained lobbying against that by the Trump administration.
However, Johnson set restrictions, barring Huawei from “core” parts of the network, such as near military facilities and nuclear sites, and capping its share of non-sensitive parts to 35 per cent.
The Trump administration has long maintained that letting Huawei build any part of the 5G network would effectively give the Chinese government access to sensitive communications.
The totality of the review means everything from the more than 10,000 US military personnel in Britain to scores of military vehicles will be looked at, not to mention intelligence operations.
The RC-135s are officially assigned to a base in Nebraska, but are effectively operated out of RAF Mildenhall in Sussex. Around half a dozen RC-135s are often at the base, where 500 Americans are stationed. They have been used recently in the Middle East.
Another issue is US agents who carry out secret missions in Britain. Sources familiar with the review questioned whether agents using personal phones and other internet-connected devices could really keep their messages safe.
Some Republicans see a pulling back in Britain as matching their belief in the need for a US military refocusing on Asia. A Republican congressional adviser said: “Britain is forcing us into a corner to make decisions and ponder consequences we don’t want to make or ponder. We would rather the special relationship be renewed and revitalised, but it is difficult to do when genuine security interests were discarded.”
It is understood that British Defence Secretary Ben Wallace was not informed of the review by counterparts when he visited Washington in March.
US National Security Adviser Robert O’Brien said UK-US intelligence cooperation would continue, but added in a joke now pointed to by Trump administration insiders, it may have to be done with “carrier pigeons”.
No 10 and the British Ministry of Defence declined to comment.
The Telegraph, London