Barack Obama and his wife Michelle have arrived at Buckingham Palace where they are being given a full ceremonial welcome by the Queen.
The couple were greeted by the Queen and Prince Philip as they emerged from the armoured presidential car.
The US leader gave the monarch a warm double handshake before turning to her husband and saying: "Nice to see you sir".
Prince Charles and the Duchess of Cornwall had met the Obamas first at the official residence of the US ambassador, Winfield House.
They had a completely private meeting before all four left for the Palace in the "Beast" - the president’s armoured limousine.
Mrs Obama looked colourful in a light blue patterned dress and a pink shrug while Camilla wore a cream outfit by Anna Valentine with a Philip Treacy hat.
The Obama's arrival
The Obama's arrival in the UK was lacking in pomp and ceremony
When they arrived at the Palace, the US president and his wife met the Duke and Duchess of Cambridge before the state visit pomp began in earnest.
They spent around 10 minutes chatting to Prince William and his new bride before the formal welcome.
The Obamas were not at the Royal Wedding last month but told Prince Charles on his US visit how America had been fascinated by the nuptials.
After about 20 minutes inside the building, the Obamas, Queen and Philip, Charles and Camilla all emerged to watch the 41-gun salute.
Mr Obama then inspected the troops with Philip while his wife and the Queen remained on the steps
