With his promise to build a wall between the US and Mexico, Donald Trump has made combatting illegal immigration a pillar of his presidency. But Mexico is already the US's firm ally in trying to push back immigration. Since its Southern Border Plan was launched in 2014, Mexico has deported around 150,000 Central American migrants each year - even though many of them are fleeing extreme violence back home. Our correspondents report from the Mexico-Guatemala border.
A programme prepared by Patrick Lovett and Aline Schmidt.