History's first Latin American pope has long made caring for migrants a priority of his pontificate, demanding that countries welcome, protect, promote and integrate those fleeing conflicts, poverty and climate disasters. Francis has also said governments are expected to do so to the limits of their capacity.
The Argentine Jesuit and President Donald Trump have long sparred over migration, including before Trump's first administration when Francis famously said anyone who builds a wall to keep out migrants was “not a Christian.”
In the letter, Francis said nations have the right to defend themselves and keep their communities safe from criminals.