Some British commentators praised the state visit as a necessary piece of realpolitik. Others criticized it as an embarrassing display for a destructive president.
The president and first lady will be hosted by King Charles III and Queen Camilla at Windsor Castle. Mr. Trump will also meet the prime minister at his country residence, Chequers.
Underground stations were closed and buses were crammed with commuters grappling with a walkout by transit workers that is expected to continue until Friday.
The British government condemned the remarks, made without evidence by the cardiologist, Dr. Aseem Malhotra, at an event for the anti-immigration party led by Nigel Farage.