The United States is warning Germany it will curb intelligence sharing with the NATO ally if it does not bar the Chinese telecommunications firm Huawei from its 5G mobile network.
The US Ambassador to Germany says he is worried the company could be a risk to the secure communication systems used for defence and intelligence co-operation.
The US has been lobbying allies to boycott Huawei.
The Chinese company rejects the allegations made by the US against it as a "smear".
A recent report from the Royal United Services Institute said a hidden ‘backdoor’ that would allow China access to data would be far easier for Huawei to build into a 5G network than it would be for the UK to detect.
The UK government is currently reviewing whether the company should be allowed to be part of Britain’s 5G network.
Defence Analyst Christopher Lee says the US is treating the prospect of Huawei's involvement in Germany very seriously:
"What they've said to the Germans is if you buy into anything we will stop trading with you."
Huawei insists it does not use any snooping technology. It says its source code is open to inspection, and denies any links to the Chinese government or intelligence services.
The US, along with New Zealand and Australia have banned Huawei from their 5G systems.