TOPSHOT - Central American migrants walk along the Mexican bank of the Rio Bravo that divides the cities of Eagle Pass, in Texas, US and Piedras Negras, in the state of Coahuila, Mexico on February 17, 2019. - Last week Trump invoked a "national emergency" to justify tapping military and other funds for barrier construction, after Congress approved less than a fourth the $5.7 billion he had sought for border security. A White House top adviser said Sunday that the president's emergency declaration could allow "hundreds of miles" of barriers to be built on the Mexican border before the 2020 election. (Photo by Julio Cesar AGUILAR / AFP)