Donald and Melania Trump arrived in the United Kingdom today for a state visit. The president and first lady "were met by The Prince of Wales and The Duchess of Cornwall on the lawn before being welcomed by The Queen on the West Terrace of Buckingham Palace," according to a post to the royal family's Instagram account.\nBut the weight of the occasion, which comes after prime minister Teresa May announced her forthcoming resignation, was overshadowed by Trump's awkward encounter with her Majesty. The president seems to have abandoned regular protocol when it came to his first physical encounter with the monarch.\nPerhaps unsure about how to greet the Queen after she extended her hand, the president appears to have clenched her first in what the Telegraph has described as a "thumb war" position. Other outlets and social media figures have called it a "fist-bump" or strange attempt at a "business power handshake."\nTrump doesn't seem to have been very gentle, either — you can see his knuckles turn white.\nWhatever it was, it must not have been pleasant for the 93-year-old Queen, who accepted it with her typical grace. Look closely, though, and you may note that her smile seems more straind than usual — maybe she's grinning through the pain. You can view the photo below.\nView this post on Instagram Today marks the start of the #USStateVisit. President Trump and Mrs. Melania Trump were met by The Prince of Wales and The Duchess of Cornwall on the lawn before being welcomed by The Queen on the West Terrace of Buckingham Palace. Upon arrival a Royal Salute was fired by The King’s Troop Royal Horse Artillery from Green Park (41 guns) and at the Tower of London by The Honourable Artillery Company (62 guns). The Guard of Honour, found by Nijmegen Company, Grenadier Guards, gave a Royal Salute before the US National Anthem, The Star-Spangled Banner, was played by the Band of the Regiment. The President @realdonaldtrump accompanied by The Prince of Wales, inspected the Guard of Honour watched by The Queen, the First Lady and The Duchess of Cornwall. A post shared by The Royal Family (@theroyalfamily) on Jun 3, 2019 at 5:42am PDT\nFor the record, there is no established protocol for foreign leaders who meet the Queen. While, according to the royal family website, her subjects may "observe the traditional forms" (curtsey, now, etc.), foreign heads of state may approach her as an equal. But a thumb war / fist bump is probably not appropriate.\nREAD ALSO: The Golden State Warriors Are Reporting That Even Canadian Hecklers Are "So Nice" And "Very Polite"\nNeither bow nor curtsey is required of US citizens, a handshake is generally given with the Queen offering her hand first. That has always been protocol - trump or no trump.— Sammy (@sammy_rufared) June 3, 2019\nPeople across the world have taken to Twitter to remark at the awkwardness of the moment. Many are wondering whether the pair are actually members of a secret society that demonstrate their allegiances through movements of the hand.\nTrump giving the Queen the Masonic handshake there #STAUNCH pic.twitter.com/5e4i2LAkrj— Lifesanocean (@lifesanocean78) June 3, 2019\nThe Queen and Trump practicing their handshake pic.twitter.com/8MX2I6rQ4N— Alexander van Twisk (@AlexanderTwisk) June 3, 2019\nMany others consider the fist bump an odd choice.\nDid Trump just fist bump the Queen? If not, it's a weird handshake. pic.twitter.com/yO6hPXFJ2X— James Armstrong (@PoliticoTeacher) June 3, 2019\nDon't know what kind of hand grip this is,but Kudos to the Queen for not letting Trump try to crush her fingers with his usual ape grip handshake! pic.twitter.com/miKrtYHOiT— LibertySister (@liberty_sister) June 3, 2019\nSome are worried about possible diplomatic and geopolitical consequences of this strong grip.\nIsn’t it dangerous for Trump to meet England’s queen in person? His excuse for a handshake could injure her and start a war.— Arunski (@Arunski) June 3, 2019\nStay tuned for more news sure to come from Trump's state visit with the Queen of Canada.\nFor more on this strange handshake, you can read this article from USA Today.