US Secretary of State Mike Pompeo said on Wednesday that the "special relationship" with Britain would thrive no matter what happened with Brexit.
Differences over Iran and Chinese communications giant Huawei's involvement in Britain's 5G development would not make a difference.
However, in a speech in London, Pompeo suggested the late, former British leader Margaret Thatcher, who was known as the Iron Lady, would have taken a firmer line with China. "Ask yourself: would the Iron Lady be silent when China violates the sovereignty of nations through corruption or coercion?"
Pompeo was in London for talks with Prime Minister Theresa May and foreign minister Jeremy Hunt a month before US President Donald Trump makes a formal state visit to London. Trump's trip will likely generate political controversy and large street protests and aerial displays.
"It was evident in my conversations both with Jeremy (foreign minister Jeremy Hunt) and with Prime Minister (Theresa) May that the special relationship does not simply endure, it is thriving," Pompeo said during a joint news conference with Hunt.
Huawei, 5G and security
However, his warm words could not hide disagreements between the two allies over Iran and particularly Huawei. Britain has indicated the Chinese company will be allowed a restricted role in building parts of its next-generation 5G communication network.
The United States has told allies not to use Huawei's equipment because of fears that it could be used by the Chinese for spying, accusations Huawei has categorically denied.
"The United States has an obligation to ensure that places where we will operate, places where American information is, places where we have our national security is at risk, that they operate inside trusted networks, and that's what we'll do," Pompeo said.
"With respect to 5G, we continue to have technical discussions, we're making our views very well known. From America's perspective, each country has a sovereign right to make its own decision about how to deal with the challenge."
British Culture Secretary Jeremy Wright separately said it was still possible that the roll-out of 5G networks in Britain could be delayed by a review into telecoms equipment, adding: "The primary intention of this process is to get the security of the network right."
"There is certainly the possibility of a delay in the process of the roll out of 5G," he told lawmakers on Wednesday. "If you want to do 5G fastest then you do that without any consideration for security."
Problems with Iran
The UK and US have also disagreed on how to approach Iran.
Pompeo had made an unannounced visit to Iraq Tuesday, instead of going to Berlin. In Baghdad, he set out US security concerns amid rising tension with Iran.
The US military said on Tuesday that B-52 bombers would be among the additional forces being sent to the Middle East to counter what Trump's administration said were "clear indications" of threats from Iran to US forces there.
On Wednesday, Iran announced it was relaxing curbs on its nuclear program under the 2015 deal with world powers, and threatened to do more.
Pompeo told reporters the United States would make decisions on how to respond after it saw what Iran's actions were. Tim Morrison, Special Assistant to the US President, told a conference in Washington to "expect more sanctions ... very soon".
Trump pulled the United States out of the nuclear deal a year ago but UK minister Hunt said on Wednesday the agreement remained an important achievement and urged Tehran to think long and hard before breaking it.
Hunt said Britain and the US had agreed that Iran should never be allowed to acquire a nuclear weapon, but had a different approach on how to achieve this.
Pompeo with May
Pompeo met with May earlier. She has been struggling for nearly three years over Britain's planned exit from the European Union after 46 years of membership.
Both Brexit and the sometimes unpredictable Trump presidency have strained relations between the world's preeminent power and its main European ally.
Pompeo said Trump was looking forward to the state visit and was eager to sign a post-Brexit free trade agreement.
av/jm (AFP, Reuters, dpa)