U.S. Secretary Of State Mike Pompeo has arrived in London at the start of a five-country tour.
Pompeo, whose visit comes as Britain prepares to leave the European Union at the end of the month, is set to meet his British counterpart, Foreign Secretary Dominic Raab, and Prime Minister Boris Johnson following their decision on January 28 to allow Chinese tech giant Huawei to take a limited role in Britain's 5G networks.
U.S. President Donald Trump has long backed Brexit and Prime Minister Boris Johnson in the hope he will set Britain on a more pro-U.S. course.
However, Johnson has sided with Europe on everything from the need to save the Iran nuclear deal that Trump abandoned to the importance of Huawei to speedy 5G mobile.
Pompeo said Britain's decision to give Huawei a limited but still leading role despite U.S. warnings was "something we'll have a conversation about."
"We will make sure that when American information passes across a network we are confident that that network is a trusted one," Pompeo told reporters on his way to London.
"It's a little unclear precisely what they're going to permit and not permit so we need to take a little bit of time to evaluate that."
Johnson told Parliament his government will "do absolutely nothing to imperil our relationship with the United States."
But a senior British official who spoke on condition of anonymity conceded that Pompeo's private dinner on January 29 with Raab and meeting with Johnson on January 30 in Downing Street might be tense.
Johnson also sounded a positive note about a Middle East peace plan that the Palestinians rejected even before Trump unveiled it alongside Israeli Prime Minister Benjamin Netanyahu on January 28.
Besides Ukraine, Pompeo will also visit Belarus, Kazakhstan, and Uzbekistan.