The US will stop sharing intelligence with countries that use Huawei hardware in their core communication systems, US Secretary of State Mike Pompeo has said.

The threat: “If a country adopts this [Huawei equipment] and puts it in some of their critical information systems, we won’t be able to share information with them, we won’t be able to work alongside them,” Pompeo said during an interview with Fox Business on Thursday. “In some cases there’s risk—we won’t even be able to co-locate American resources, an American embassy, an American military outpost,” he added. 

Defiance: Britain, New Zealand, and Germany all signaled this week that they may be willing to continue using Huawei gear as they prepare their infrastructure for the arrival of 5G. Pompeo’s remarks are a major escalation in tensions between the US and its allies over the role of Huawei.

American concerns: It’s got a lot to do with the role of 5G and whether China could use security back doors to exert undue control over a nation’s digital infrastructure via Huawei’s equipment. Confusingly, on the same day as Pompeo’s comments, President Donald Trump tweeted that he wanted the US to win in 5G development “through competition, not by blocking out currently more advanced technologies.”

Denials: In an interview with the BBC this week, Huawei founder Ren Zhengfei said the company has never installed back doors into its technology and never would do so, even if required to by Chinese law.