STATE DEAPRTMENT - This week Secretary of State Mike Pompeo heads to London as British officials weigh whether or not to allow Chinese telecom giant Huawei to take part in the country's buildout of its 5G network.

The British government is expected to make the decision Tuesday.  CNBC reported London is expected to grant Huawei some access to its 5G network.

The State Department said U.S. Secretary of State Mike Pompeo is meeting with Prime Minister Boris Johnson and Foreign Secretary Dominic Raab to reaffirm the “special relationship” between the two countries.

A senior U.S. official said the two nations are having “very close” and “very vigorous conversations.” Another official said Britain has not told the U.S. about the final decision.  

The U.S. says Huawei could provide China a “back door” for spying, a claim that Huawei rejects.  

In a Friday phone call with Johnson, U.S. President Donald Trump told the British Prime Minister that giving Huawei the go-ahead would cause a major rift in transatlantic relations and jeopardize intelligence-sharing between Washington and London.

U.S. officials have also voiced frustration with decisions by some European nations to grant Huawei some access in the roll-out of their 5G network.

“They announced a toolkit that many of us consider to be inadequate,” a senior U.S. official said, referring to German Chancellor Angela Merkel’s "no-spy" pact from Huawei as she decided to allow the Chinese telecom company to take part in Germany’s 5G roll-out.

Under the National Defense Authorization Act for Fiscal Year 2020, the U.S. Defense Secretary should brief Congressional defense committees by March 15 on the implementation of a plan for fifth generation information and communications technologies, including steps to work with U.S. allies and partners to protect critical networks and supply chains.