US Secretary of State Mike Pompeo predicted Thursday that Brexit would bring "enormous benefits" to the United States and the UK, as he wound down a visit to Britain on the eve of its historic departure from the European Union.
The chief US diplomat also played down a dispute about Britain's decision to plug in Chinese technology into its next-generation mobile network, suggesting that Washington would continue sharing intelligence with London.
"There were things that the United Kingdom was required to do as part of being a member of the EU, and they'll be able to do them differently now," Washington's top diplomat told a think-tank audience in London.
"Some of this will be worked out through the free trade agreement, some of it will be worked out by entrepreneurs just kicking it," he said, alongside British Foreign Secretary Dominic Raab.
"You will see the enormous benefits that accrued to both of our nations as a result of this."
Britain will enter a new chapter when it becomes the first country to quit the EU's institutions at midnight Brussels time (2300 GMT) on Friday.
"It is a great moment for our country... a moment of hope and opportunity," British Prime Minister Boris Johnson said Wednesday, as he prepared to address the nation at 2200 GMT Friday -- an hour before Brexit.
Pompeo paid a courtesy visit to Johnson before flying to Kiev, the second leg of his five-nation tour that includes four former Soviet republics.
Although Britain will remain under most EU rules during an 11-month transition period, it is then likely to lose privileged access to the single European market -- the world's largest and most important for UK trade.
Johnson has argued he can negotiate ambitious free trade agreements with both his 27 former partners and the US, but has seen recent strains in the so-called "special relationship" with Washington.
Britain has been angered by American refusal to extradite the wife of a US diplomat who is using the cover of diplomatic immunity to avoid prosecution over the death of a teenager in a road accident in England.
Johnson's hopes for a US trade deal are also complicated by US President Donald Trump's unpopularity in Britain and domestic pressure to stand up to Washington.
The British premier has defied expectations since taking power last July by failing to side with the United States on everything from the Iran nuclear deal, which Trump has abandoned, to working with Chinese tech giant Huawei.
Trump -- a long-time fan of Brexit and Johnson's ability to deliver it successfully -- has publicly urged Britain to rethink, yet has so far been restrained in his criticism.
But others, including Republican senators who will have to sign off on a future US-UK trade deal, have cautioned that sharing intelligence and striking an agreement could be imperilled by the Huawei decision in particular.
Pompeo sounded a more positive note on Thursday.
He said the US-UK intelligence sharing relationship would remain "deep" and "strong" and that he was "confident" the next generation of technology would be secure.
However, he warned strongly about Beijing's growing global influence, calling China's ruling Communist Party "the central threat of our times" that challenges Western principles.
'Long Live Europe'
Britons narrowly backed departing the EU in a 2016 referendum that left the country locked in political crisis and acrimonious division.
Johnson, who headed the pro-Leave campaign, won a thumping election victory in December on the mantra "get Brexit done".
That is now finally happening, with Britain's departure set in European law Wednesday, amid emotional scenes, as the bloc's parliament voted to ratify the divorce papers.
"We will always love you and we will never be far," said EU Commission president Ursula von der Leyen, adding: "Long live Europe."
Britain's eurosceptic lawmakers were in triumphant mood after two decades as a thorn in Brussels' side, brandishing British flags in contravention of the chamber's rules.