Barack Obama

U.S. President Barack Obama and former President Bill Clinton walk past the Rose Garden to host an event marking the 20th anniversary of the national service program AmeriCorps at the White House in Washington September 12, 2014. In 1993, Clinton signed the bill that created AmeriCorps.

Kevin Lamarque/Reuters

U.S. President Barack Obama and former President Bill Clinton walk past the Rose Garden to host an event marking the 20th anniversary of the national service program AmeriCorps at the White House in Washington

U.S. President Barack Obama and British Prime Minister David Cameron, left, watch a flypast on the second day of a NATO summit at the Celtic Manor Resort in Newport, Wales on Friday, Sept. 5, 2014.

Matt Dunham/AP

U.S. President Barack Obama and British Prime Minister David Cameron, watch a flypast on the second day of a NATO summit at the Celtic Manor Resort in Newport, Wales on Friday

Underclassmen listen from the back of the stadium as U.S. President Obama speaks at a commencement ceremony at the United States Military Academy at West Point...Underclassmen listen from the back of the stadium as U.S. President Barack Obama speaks at a commencement ceremony at the United States Military Academy at West Point, New York, May 28, 2014. Obama's commencement address here is the first in a series of speeches that he and top advisers will use to explain U.S. foreign policy in the aftermath of conflicts in Iraq and Afghanistan and lay out a broad vision for the rest of his presidency. REUTERS/Kevin Lamarque

Kevin Lamarque/Reuters

Underclassmen listen from the back of the stadium as U.S. President Barack Obama speaks at a commencement ceremony at the United States Military Academy at West Point, New York. Obama’s commencement address here is the first in a series of speeches that he and top advisers will use to explain U.S. foreign policy in the aftermath of conflicts in Iraq and Afghanistan and lay out a broad vision for the rest of his presidency 

Barack Obama, Michelle Obama, Michael Bloomberg, Bill Clinton, Hillary Rodham Clinton...President Barack Obama and first lady Michelle Obama, along with former Secretary of State Hillary Rodham Clinton and former President Bill Clinton tour the Memorial Hall at the National September 11 Memorial Museum with former New York Mayor Michael Bloomberg, Thursday, May 15, 2014, in New York.

Carolyn Kaster/AP

President Barack Obama and first lady Michelle Obama, along with former Secretary of State Hillary Rodham Clinton and former President Bill Clinton tour the Memorial Hall at the National September 11 Memorial Museum with former New York Mayor Michael Bloomberg, Thursday 

An anti-US protester dressed like the St...An anti-US protester dressed like the Statue of Liberty stands next to a giant mock US flag during a protest near the Malacanang palace in Manila on April 29, 2014, as US President Barack Obama's visit to the capital winds down. The protesters were protesting against the newly-signed defense agreement between the US and the Philippines, with President Obama ending an Asian tour April 29 with a warning to China against using force to resolve territorial disputes, and an "ironclad" promise of military support for the Philippines.     AFP PHOTO/TED ALJIBETED ALJIBE/AFP/Getty Images

Ted Aljibe/AFP

An anti-US protester dressed like the Statue of Liberty stands next to a giant mock US flag during a protest near the Malacanang palace in Manila, as US President Barack Obama‘s visit to the capital winds down. The protesters were protesting against the newly-signed defense agreement between the US and the Philippines. 

U.S. President Obama walks with Japan's Emperor Akihito and his wife Empress Michiko past an honour guard with Japan and U.S. flags during an official arrival ceremony at the Imperial Palace in Tokyo...U.S. President Barack Obama walks with Japan's Emperor Akihito (3rd L) and his wife Empress Michiko (L) past an honour guard with Japan and U.S. flags during an official arrival ceremony at the Imperial Palace in Tokyo April 24, 2014. Obama will use a state visit to Japan on Thursday to try to reassure Asian allies of his commitment to ramping up U.S. engagement in the region, despite Chinese complaints that his real aim is to contain Beijing's rise. REUTERS/Jim Watson/Pool

Jim Watson/Reuters

US president Barack Obama with Japan’s emperor Akihito and empress Michiko pass an honour guard during an arrival ceremony at the Imperial Palace in Tokyo 

U.S. President Barack Obama waves as he leaves Rome's airport...U.S. President Barack Obama waves as he leaves Rome's airport March 28, 2014. REUTERS/Giampiero Sposito  (ITALY - Tags: POLITICS)

Giampiero Sposito/Reuters

U.S. President Barack Obama waves as he leaves Rome‘s airport. 

Pope Francis and President Barack Obama smile as they exchange gifts, at the Vatican Thursday, March 27, 2014. President Barack Obama called himself a "great admirer" of Pope Francis as he sat down at the Vatican Thursday with the pontiff he considers a kindred spirit on issues of economic inequality. Their historic first meeting comes as Obama's administration and the church remain deeply split on issues of abortion and contraception. (AP Photo/Gabriel Bouys,

Gabriel Bouys/AP

Pope Francis and US President Barack Obama exchange gifts at the Vatican on Thursday. It is their first meeting.

Pope Francis Meets President Obama...VATICAN CITY, VATICAN - MARCH 27:  The silhouette of US President Barack Obama is seen as he arrives in his car at the San Damaso courtyard for a meeting with Pope Francis on March 27, 2014 in Vatican City, Vatican. This is Obama's first audience with Pope Francis and it is the second time that he has been received at the Vatican, after an audience with Pope Benedict XVI on July 10, 2009. Barack Obama is the ninth US President to make an official visit to the Vatican. The first, Woodrow Wilson, received by Pope Benedict XV after the end of the First World War.  (Photo by Franco Origlia/Getty Images)

Franco Origlia/Getty

US President Barack Obama arrives at the San Damaso courtyard for a meeting with Pope Francis in Vatican City, Vatican. This is Mr Obama’s first audience with Pope Francis, and it is the second time he has been received at the Vatican, after an audience with Pope Benedict XVI on July 10 2009. He is the ninth US president to make an official visit to the Vatican. The first, Woodrow Wilson, was received by Pope Benedict XV after the end of World War I.

A US army officer escorts US President Barack Obama (2nd-L), Belgium's King Philippe (2nd-R) and Belgian Prime Minister Elio Di Rupo (R) as they visit the WWI Flanders Field Cemetery in Waregem on Wednesday. The cemetery is the final resting place for 368 Americans, most of whom were killed during World War I. Obama will pay his first visit ever to the EU headquarters in Brussels, cementing US-EU opposition to the takeover of Crimea after hitting out at Russian expansionism as a "sign of weakness".

Belga/AFP

A US army officer escorts US President Barack Obama (2nd-L), Belgium’s King Philippe (2nd-R) and Belgian Prime Minister Elio Di Rupo (R) as they visit the WWI Flanders Field Cemetery in Waregem on Wednesday. The cemetery is the final resting place for 368 Americans, most of whom were killed during World War I. Obama will pay his first visit ever to the EU headquarters in Brussels, cementing US-EU opposition to the takeover of Crimea after hitting out at Russian expansionism as a “sign of weakness”.