President Trump seems to think that holding children and families in federal government custody without beds, soap, toothbrushes or even adequate food might stem migration from Central America. Recent reporting on these conditions in migrant detention facilities has intensified critiques of this administration’s brutal approach to the families who are coming in record numbers to our southern border. In an apparent response to that scrutiny, Mr. Trump said in a tweet, “If Illegal Immigrants are unhappy with the conditions in the quickly built or refitted detentions centers, just tell them not to come. All problems solved!"

The suggestion that subjecting migrants to appalling conditions might serve as a deterrent is not just cruel; it conveys a grave misunderstanding of the forces that drive people to undertake this dangerous journey and of what it will take to manage the number of people arriving at the border.

That’s why, while Democratic members of Congress and presidential candidates are rightly drawing attention to the plight of migrants, they need to do more than condemn the current conditions; they need to show that unlike Mr. Trump, they understand the nature of the crisis, both at the border and at its origins in Central America. And they need to offer the country a workable plan to address it.

The first thing that elected representatives and candidates need to make clear in their discussions of immigration — and that Mr. Trump’s “just tell them not to come” rhetoric ignores — is that the surge in migration we have seen is not simply a border management issue. This is a refugee and humanitarian crisis in our backyard, fueled by the inability of governments in El Salvador, Guatemala and Honduras to protect their own citizens from violence perpetrated by armed gangs and drug traffickers who act with impunity. It is also fueled by economic desperation, the impact of climate change in the region and a host of other challenges that this administration is ignoring as it grapples with the migration that ensues.