By Kylie MacLellan
LONDON (Reuters) - U.S. Secretary of State Mike Pompeo said on Wednesday that the "special relationship" with Britain would thrive whatever happened with Brexit, and despite differences over Iran and the involvement of China's Huawei in Britain's 5G communications network.
Pompeo came to London for talks with Prime Minister Theresa May and foreign minister Jeremy Hunt a month before U.S. President Donald Trump makes a formal state visit likely to generate political controversy and large street protests.
"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 told a joint news conference with Hunt.
However, his warm words did not mask disagreements between the two allies over Iran and particularly Huawei, which Britain has indicated will be allowed a restricted role in building parts of its next-generation communication networks using 5G technology.
The United States has told allies not to use Huawei's equipment because of fears that it could be a vehicle for Chinese spying, accusations Huawei has categorically denied.
"The United States has an obligation to ensure that places where we want to operate, places where American information is, places where we have our national security resident, they operate inside trusted networks," 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."
The two countries have also disagreed on how to approach Iran.
Pompeo had made an unannounced visit to Iraq on Tuesday where he set out U.S. security concerns amid rising tension with Iran.
The U.S. 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 says are "clear indications" of threats from Iran to U.S. forces there.
On Wednesday, Iran announced it was relaxing curbs on its nuclear programme under the 2015 deal with world powers, and threatened to do more -- including enriching uranium to a higher level -- if other countries did not shield it from U.S. sanctions.
Pompeo told reporters the United States would make decisions on how to respond when it saw what Iran's actions were. Tim Morrison, Special Assistant to the 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 Hunt said on Wednesday the agreement remained an important achievement and urged Tehran to think long and hard before breaking it.
He said Britain and the United States agreed that Iran should never be allowed to acquire a nuclear weapon, but had a different approach on how to achieve this.
Earlier, Pompeo met May, who has been grappling for three years with a political crisis over Britain's planned exit from the European Union.
As Britain tries to extract itself from the EU after 46 years of membership, a divorce many diplomats say has already made Britain weaker, Pompeo was due to give a speech on the "special relationship".
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.
(Reporting by Guy Faulconbridge, Kate Holton and William Schomberg; writing by Michael Holden; Editing by Janet Lawrence and Kevin Liffey)