A handout picture provided by the Saudi Royal Palace on June 17, 2016 shows deputy crown prince and Minister of Defence, Prince Mohammed bin Salman (L) meeting with US President Barack Obama in Washington. / AFP PHOTO / Saudi Royal Palac AND AFP PHOTO / BANDAR ALGALOUD / === RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / HO / SAUDI ROYAL PALACE" - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS ===BANDAR ALGALOUD/AFP/Getty Images

WASHINGTON, DC - JUNE 17: A U.S. Secret Service agent keep watch as President Barack Obama and the first family lift off from the South Lawn and leave the White House June 17, 2016 in Washington, DC. The first family is traveling to New Mexico and tour Carlsbad Caverns National Park to celebrate the 100th anniversary of the creation of America's national park system. (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - JUNE 17: Senior Vice President of People for the Ethical Treatment of Animals (PETA) Dan Mathews shouts slogans during a demonstration outside a National Rifle Association (NRA) location on June 17, 2016 in Washington, DC. PETA held a rally to call for an end to all gun violence, including by hunters. (Photo by Alex Wong/Getty Images)

WASHINGTON, DC - JUNE 17: Senior Vice President of People for the Ethical Treatment of Animals (PETA) Dan Mathews holds mounted animals during a demonstration outside a National Rifle Association (NRA) location on June 17, 2016 in Washington, DC. PETA held a rally to call for an end to all gun violence, including by hunters. (Photo by Alex Wong/Getty Images)

US President Barack Obama walks with his daughter Malia (2nd R), First Lady Michelle Obama (L) and daughter Sasha as they depart the White House in Washington, DC, June 17, 2016. The family is headed to New Mexico and California. / AFP PHOTO / JIM WATSONJIM WATSON/AFP/Getty Images

WASHINGTON, DC - JUNE 17: Marine One, with U.S. President Barack Obama and the first family on board, flies over the Jefferson Memorial after departing the White House June 17, 2016 in Washington, DC. The first family is traveling to New Mexico and tour Carlsbad Caverns National Park to celebrate the 100th anniversary of the creation of America's national park system. (Photo by Chip Somodevilla/Getty Images)

US President Barack Obama waves while walking with his daughter Malia as they depart the White House in Washington, DC, June 17, 2016. The family is headed to New Mexico and California. / AFP PHOTO / JIM WATSONJIM WATSON/AFP/Getty Images

WASHINGTON, DC - JUNE 17: A U.S. Secret Service agent keep watch as President Barack Obama and the first family lift off from the South Lawn in Marine One and leave the White House June 17, 2016 in Washington, DC. The first family is traveling to New Mexico and tour Carlsbad Caverns National Park to celebrate the 100th anniversary of the creation of America's national park system. (Photo by Chip Somodevilla/Getty Images)