Mixing pageantry and political pugilism, President Donald Trump opened a state visit to Britain on Monday by drawing a smile from Queen Elizabeth II and stepping up a long-running feud with London's anti-Trump mayor before his plane had touched down on English soil.
He may warn security collaboration between the two countries could be at risk if Britain allows Huawei to help roll out Britain's 5G phone network, echoing threats by U.S. secretary of state Mike Pompeo last month.
Mr Trump has praised a more radical Brexit-supporting potential successor to Mrs May, and his envoys have urged a tougher British stance towards Chinese telecoms giant Huawei.
Moments before Air Force One landed at Stansted, Donald Trump posted two tweets criticising the Mayor of London.
Britain's relationship with the U.S. is an enduring alliance, but some British voters see Mr Trump as crude, volatile and opposed to their values on issues ranging from global warming to his treatment of women.
Huge protests are being organized in London, with organizers crowdfunding a bright orange "baby Trump" blimp depicting the United States leader in a diaper - aiming for an even larger version than the one flown during his visit previous year.
America's leader is a man who inspires strong views on all sides - and that was evident in central London on the first day of his United Kingdom trip.
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Some have also complained that they detract from the beauty of Venice's historic sites and bring too many tourists. The MSC Opera cruise liner stand by a tourist boat following a collision in Venice , Italy, Sunday, June 2, 2019 .
While some around the palace supported Mr Trump, one Londoner was so angry she had chose to come out in protest. But many Britons, including senior politicians, oppose the visit, whereas Obama was welcomed enthusiastically and the queen was known to have a warm relationship with him and Michelle Obama.
At the conclusion of his United Kingdom visit, Trump will depart for Ireland, where he's set to meet Irish Prime Minister, or Taoiseach, Leo Varadkar.
Trump also said he "wouldn't pay" the $50 billion so-called "divorce bill" to settle the U.K.'s financial obligations with the European Union: "I'm only saying this from my stand point".
"There are so many things about President Donald Trump's policies that are the antithesis of our values in London, but also our values as a country".
On Tuesday, the Trumps will spend much of their time with Prime Minister Theresa May. Demonstrators are expected, including the possible return of an inflatable balloon depicting the president as a baby.
Ivanka Trump, daughter of President Trump, and her husband Jared Kushner, special adviser to the president, visit Westminster Abbey in central London with Treasury Secretary Steven Mnuchin (right) on June 3, 2019.
Trump is expected to face significant public protests in Britain as well as a royal welcome.