LONDON — President Barack Obama will outline in a speech today how much the world has changed since the U.S.-British partnership emerged victorious from World War II, but also argue that the relationship remains the cornerstone of global security.
The theme, outlined by administration officials here Tuesday, is part celebration of the military partnership, which has waged war in three Muslim nations over the past decade, and part reassurance that the heavy cost has been essential.
Obama will deliver the address, characterized by advisers as "the anchor speech" of his six-day European trip, to the British Parliament at Westminster Hall, becoming the first American leader to do so in that historic venue.
"He'll speak to the fact that we've obviously come through a very difficult decade, but in some respects we're turning a corner," Ben Rhodes, a U.S. deputy national security adviser, told reporters.
His address at Westminster Hall will be the most substantive event of the trip so far after a start heavy with ceremony.
On Tuesday, Queen Elizabeth II welcomed Obama and the first lady, Michelle Obama, for his first state visit here. The official greeting took place just before noon at Buckingham Palace.
America's first couple walked up the red carpet to the palace door, where the queen, her ubiquitous handbag in the crook of her arm, greeted them with a handshake and smile. Prince Philip stood by her side.
The Obamas' gift to the queen was a handmade, leather-bound album containing original photographs of the June 1939 visit to the United States of her parents, King George VI and his consort Elizabeth, known more recently as the queen mother.
Inside the palace, the Obamas also met with Prince William and new wife Kate, the Duke and Duchess of Cambridge.
Many lined the streets and gathered outside the Obamas' tour sites on a warm and clear afternoon.
The Obamas visited Westminster Abbey and laid a wreath at a tomb in memory of "the unknown warrior." Obama wrote in the guest book, "It is a great privilege to commemorate our common heritage and common sacrifice," but added the wrong date, "24 May 2008."
Obama also paid a courtesy call at 10 Downing Street to see Prime Minister David Cameron, with whom he will hold more extensive meetings today.
The evening ended with a state dinner at Buckingham Palace, where Obama, in white tie and tails, toasted the alliance as "a commitment that speaks to who we are."