Thousands of officers will be on duty as Donald Trump's visit is met by the biggest UK police operation since the August 2011 riots.
Police from nearly every force have been called up for the US president's arrival, as demonstrators prepare to protest against his first trip to the UK.
Mr Trump is expected to avoid central London, where the bulk of protests will take place, instead visiting Blenheim Palace, Chequers, and Windsor Castle during his trip on Thursday and Friday.
The security operation is estimated to cost between £8m and £10m and will put police under "unquestionable pressure", according to Police Federation chairman Simon Kempton, who said operations were likely to become "merely reactive" during the visit.
Police specialists from firearms, public order, traffic and special escort teams will all be involved in making sure the controversial trip goes smoothly.
Assistant Chief Constable Chris Shead, from the National Police Coordination Centre, said: "Police forces are working together on a significant, multi-faceted security operation supporting the presidential visit to the UK.
"Nearly all police forces in England and Wales are providing officers and resources to assist with the operations in areas hosting the visit."
Police chiefs have warned the massive deployment will have an impact for months, as officers take days off for Trump-related overtime and potentially cause difficulty for colleagues left behind.
The president comes to the UK from a NATO summit where he again ruffled feathers, claiming Germany was "captive" to Russia over its energy supply; and suggesting members should commit to spending 4% of their GDP on defence – double the current goal.
While in the UK, he is set to travel between locations in his bulletproof "Beast" limousine, surrounded by dozens of police and security service vehicles.
As well as meeting the Queen at Windsor, also on Mr Trump's schedule is a journey to Scotland where he owns two golf courses and will spend the weekend.
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Mr Trump this week described the UK as a country "in turmoil", alluding to the political drama that saw David Davis and Boris Johnson ministers resign over the prime minister's Brexit plans.
He said it was "up to the people" whether Theresa May remains as PM and suggested he would make time to visit his "friend", former foreign secretary Mr Johnson.