The US has been lobbying its allies to boycott Huawei due to national security risks.
The Wall Street Journal said it has seen a memorandum from Donald Trump ambassador Dick Grenell to the German government threatening that it won't tell it about terrorist threats if it continues to deploy Huawei 5G infrastructure.
The US believes that allowing the Chinese company Huawei to construct and maintain 5G networks will give the Chinese government a backdoor into communications surveillance.
Among other things, European security agencies have relied heavily on USA intelligence in the fight against terrorism. The U.S. has additional concerns about the use of Chinese personnel, such as whether Huawei will allow oversight from security services, according to the paper. "And we will, of course, discuss this issue with our partners in Europe and with relevant USA departments, that goes without saying", Merkel told reporters when asked about Huawei's involvement in developing German telecommunications infrastructure. Further, the USA likely needs its allies to support the pushback against Huawei in order for the isolation tactic to have any meaningful effect.
The Chinese telecoms behemoth has strenuously denied the espionage allegations.
While the U.S. embassy in Berlin would not confirm that a message was sent, the German Federal Economics Ministry did tell the Frankfurter Allgemeine Zeitung (FAZ - auf deutsch) that the letter had been received and would be "answered promptly". Germany recently announced all electronics purchased for its mobile networks will be required to pass testing by the Federal Office for Information Security (BSI), and network operators will be strongly encouraged to buy equipment from a variety of suppliers to prevent any single company from developing a monopoly.
The German Economy Ministry confirmed that the letter had been received.
The year ended with the arrest of Huawei's chief financial officer in Canada at U.S. request, to the consternation of China.