WASHINGTON, DC - JULY 12: (AFP OUT) With U.S. President Barack Obama and first lady Michelle Obama on board, Marine One lands on the South Lawn of the White House with July 12, 2016 in Washington, DC. The Obamas were returning from Dallas where they attended a public memorial service for the five Dallas police officers who were killed by a sniper last week during a Black Lives Matter demonstration. (Photo by Chip Somodevilla/Getty Images)