Barack Obama is to meet the Queen at Buckingham Palace later at the start of his packed, three-day state visit.
He will meet Prime Minister David Cameron for talks on Wednesday likely to focus on Libya and the Middle East.
Mr Obama arrived in the UK a day ahead of schedule on Monday, to avoid any disruption from a volcanic ash cloud.
He flew into Stansted, in Essex, with wife Michelle after leaving the Republic of Ireland, where his week-long tour of Europe began.
The couple will receive a ceremonial welcome later, before visiting Westminster Abbey and Downing Street.
In a joint article in the Times, Mr Obama and Mr Cameron said of their countries' relationship: "Ours is not just a special relationship, it is an essential relationship - for us and for the world.
"When the United States and Britain stand together, our people and people around the world can become more secure and more prosperous.
"The reason it thrives is because it advances our common interests and shared values. It is a perfect alignment of what we both need and what we both believe."
Analysis
Whenever a US president comes here there is always a slightly tortuous debate on whether or not the relationship is still special or not.
Both sides have decided the best way of avoiding that debate is to come up with a new wording entirely. They have a new adjective. It is now an essential relationship.
In a joint article for the Times newspaper, the prime minister and the president say the relationship between their countries was based originally on what they called emotional connections, sentiment and the ties of people and culture but now it thrives on common interests and shared values.
So what they are trying to focus on here now is more business-like pragmatism rather than any idea of appealing to the mythology of past historic links.
Both sides have decided the best way of avoiding that debate is to come up with a new wording entirely. They have a new adjective. It is now an essential relationship.
In a joint article for the Times newspaper, the prime minister and the president say the relationship between their countries was based originally on what they called emotional connections, sentiment and the ties of people and culture but now it thrives on common interests and shared values.
So what they are trying to focus on here now is more business-like pragmatism rather than any idea of appealing to the mythology of past historic links.
They also vowed not to abandon the protesters fighting for democracy in Arab countries, writing that they would "stand with those who want to bring light into dark, support those who seek freedom in place of repression, aid those laying the building blocks of democracy.
"We will not stand by as their aspirations get crushed in a hail of bombs, bullets and mortar fire," said the two leaders."We are reluctant to use force, but when our interests and values come together, we know we have a responsibility to act."
Mr Obama's week-long tour of Europe began in Dublin on Monday where he delivered an open-air speech to thousands of cheering people, reaffirming US-Irish ties.
Speaking in stilted Gaelic, he told them he was happy to be in the Republic of Ireland.
"Whenever peace is challenged... America will stand by you always in your pursuit of peace," he said.
The president's Air Force One jet landed at Stansted airport just after 2215 BST on Monday.
The Prince of Wales and Duchess of Cornwall were originally due to greet the Obamas but because of their early arrival the couple were met instead by the Lord in Waiting, Viscount Brookeborough.
Mr and Mrs Obama will stay at Buckingham Palace on Tuesday but are spending their first night in the UK at Winfield House, the American ambassador's residence in central London.
Security will be tight during the three-day trip which comes ahead of the G8 summit of world leaders in France.
The state visit to the UK is the 101st to be hosted by the Queen but only the third involving a US president in 100 years. The last US leader to come to the UK on one was George Bush in 2003.
President Obama was given a warm welcome in Dublin at the start of his week-long tour of Europe The public will get their first chance to see President Obama and the First Lady when they arrive at Westminster Abbey to lay a wreath at the Tomb of the Unknown Warrior.
The couple will then go to Downing Street to meet the prime minister and his wife, Samantha, before returning to Buckingham Palace to meet Labour leader Ed Miliband.
In the evening there will be a state banquet for the Obamas at Buckingham Palace, where they will stay overnight.
On Wednesday, Mr Obama will hold talks with Mr Cameron at Downing Street.
He will be joined later by Michelle for a barbecue at Number 10 with British and American military veterans.
There will be a news conference, before the president departs for the Houses of Parliament, where he will give a speech about US foreign policy to MPs in Westminster Hall.
The day will be rounded off with a return banquet at Winfield House, the official residence of the US ambassador, where the Queen will formally say farewell.
Later this week President Obama will visit Poland and France, where he will attend a meeting of the Group of Eight (G8) major world powers.
US President Barack Obama and First Lady Michelle Obama arrive at Stansted Airport
0 comments