Pompeo, speaking on Thursday, also dismissed Huawei CEO Ren Zhengfei's assertions that his company would never share user secrets, and said he believed more American companies would cut ties with the tech giant.
But EE Chief Executive Mark Allera told reporters the use of Huawei 5G devices had now been paused until it could be confident that devices would be supported for their lifetime.
Huawei handsets had been expected to be among the devices available on the new superfast networks. "We will keep this situation under review".
SoftBank had been due to release a Huawei-made smartphone on Friday, but halted the release "because we are now trying to confirm if our customers will be able to use the equipment with a sense of safety", company spokesman Hiroyuki Mizukami told AFP.
Washington has added Huawei and its affiliates to its "Entity List", a move that bans the company from buying parts and components from American firms without USA government approval.
United States authorities this week, in any case, issued a 90-day relief on the restriction on managing Huawei, saying breathing space is expected to stay away from enormous disturbance.
New details emerge on Huawei’s potential plans to go forward without Google
Still, he stressed that would only happen if the company were completely stopped from using Google's and Microsoft's software. It means you can probably abandon any hope of seeing Android Q on any Huawei devices.
NTT Docomo announced shortly afterward that it was halting pre-orders of a Huawei handset due to be released this summer, without giving a reason for the decision.
Japanese conglomerate Panasonic Corp joined a growing list of global companies that is disengaging from Huawei Technologies Co Ltd, the world's second-largest seller of smartphones and the largest telecom-gear maker, saying it had stopped shipments of some components.
China has retaliated with its own levies on USA imports, but it was Washington's subsequent move against Huawei that took the trade war into a new phase, stoking fears about risks to global growth and knocking financial markets.
US Secretary of State Mike Pompeo warned Britain during a visit to London that it risked undermining the historic allies' intelligence sharing.
EE said it's working with Huawei and Google, which makes the Android mobile operating systems to make sure it "can carry out the right level of testing and quality assurance".