President Obama greets residents of Joplin, Mo., during his visit Sunday to the devastated city. He praised Joplin's residents for their remarkable courage during and after the May 22 tornado. (Associated Press)
President Obama embraces residents of Joplin, Mo., while viewing the devastation caused by a May 22 tornado that left at least 139 people dead. Mr. Obama promised the nation will not forget the city and its people. (Associated Press)
Residents hold up signs as President Barack Obama views damage from the tornado that devastated Joplin, Mo., Sunday, May 29, 2011. (AP Photo/J. Scott Applewhite)
President Barack Obama, left, reaches out to residents while viewing damage from the tornado that devastated Joplin, Mo., Sunday, May 29, 2011. (AP Photo/J. Scott Applewhite)
President Obama arrives at the Joplin Regional Airport in Joplin, Mo., on Sunday, May 29, 2011, to view damage caused by a devastating tornado that hit the area last Sunday and to take part in a memorial service for the victims. (AP/Mike Gullett)
President Obama boards Air Force One at Andrews Air Force Base outside Washington on his way to visit tornado victims in Joplin, Mo., on Sunday, May 29, 2011. (AP Photo/J. Scott Applewhite)
President Obama (left) and Polish Prime Minister Donald Tusk talk as they leave a joint news conference at the Chancellery Building in Warsaw on Saturday, May 28, 2011. (AP Photo/Carolyn Kaster)
US President Barack Obama, right, shares a word with IMF Acting Managing Director John Lipsky, center, and British Prime Minister David Cameron during departures after a G8 summit in Deauville, France, Friday, May 27, 2011.
President Obama (right) speaks with Egyptian Prime Minister Essam Sharaf during a group photo at the G8 summit in Deauville, France, on May 27, 2011. (Associated Press/dapd/Peer Grimm)
French President Nicolas Sarkozy (right) and his wife, Carla Bruni-Sarkozy (center), welcome President Obama to Le Ciro's Restaurant during a dinner meeting for the G8 summit in Deauville, France, on May 26, 2011. (Associated Press)
President Obama meets with Japanese Prime Minister Naoto Kan at the G-8 summit in Deauville, France, on Thursday, May 26, 2011. (AP Photo/Charles Dharapak)
President Obama meets with Russian President Dmitry Medvedev on the sidelines of the G-8 summit in Deauville, France, on Thursday, May 26, 2011. (AP Photo/Charles Dharapak)
Demonstrators in London on May, 24, 2011, call for a free Syria outside Buckingham Palace, where President Obama is staying during a State visit to Britain. (Associated Press)
President Obama (center) — escorted by John Bercow (center left), speaker of the House of Commons, and Baroness Hayman (center right), lord speaker of the House of Lords — arrives at the Palace of Westminster in London on Wednesday, May 25, 2011, for an address to both houses of Parliament. (AP Photo/Sang Tan, Pool)
President Obama and British Prime Minister David Cameron participate in a joint news conference at Lancaster House in London on Wednesday, May 25, 2011. (AP Photo/Charles Dharapak)
President Obama and Britain's Prince Philip review the Scots Guard during an official arrival ceremony at Buckingham Palace in London on Tuesday. (Associated Press)
Britain's Queen Elizabeth II and Mr. Obama toast at a state banquet in London's Buckingham Palace on Tuesday. Mr. Obama brought gifts for the queen and other members of the British royal family. (Associated Press)
President Obama (left) and British Prime Minister David Cameron react as they play table tennis with students during a visit to the Globe Academy in London on Tuesday, May 24, 2011. (AP Photo/Charles Dharapak)
President Obama (left) and British Prime Minister David Cameron high-five as they play table tennis at Globe Academy in south London on Tuesday, May 24, 2011. (AP Photo/Paul Hackett, Pool)