Bloomberg News recently reported that pandemic-induced economic deprivation, two fierce hurricanes and the hope that a new administration might ease security threaten to create a new wave of migrants at America’s southern border. “There are going to be caravans, and in the coming weeks it will increase,” said the head of a civil-society organization in Guatemala.

With the pandemic far from beaten, the issue has a pressing new public-health dimension, making the problem harder than ever. President-elect Joe Biden may have to grapple with all this during his first weeks in office.

President Donald Trump’s response to the migrant challenge was awful, but mayhem at the border didn’t start with him. Biden needs to correct mistakes that go further back – including errors by the administration he was a part of. Unlike Trump, President Barack Obama didn’t make family separation a deliberate instrument of policy, part of a “zero tolerance” approach to scare migrants into staying away. But separations did occur – and thanks to a tight reading of certain statutes, children were jailed. Undocumented immigrants flooded the border. Deportations ran at higher rates than during the Trump years.

The new administration ought to reflect on this experience. It should temper any messaging that might suggest, “Our borders are now open.” Biden’s vow to suspend all deportations for 100 days is understandable given the pandemic, but border detentions are already increasing. His officials should look carefully at Trump’s agreements with Guatemala, El Salvador and Honduras to allow asylum requests to be heard there rather than allowing refugees to continue through Mexico to the U.S. border. Reflexively sundering those deals would be foolish.

At the same time, the U.S. needs to bolster its immigration courts, by restoring judicial discretion in asylum cases and adding more lawyers and judges to reduce the asylum backlog. And it shouldn’t need saying that every effort must be made to reunite separated children with their parents.

The temptation to flip a switch and reverse everything the Trump administration did on migration is understandable. Many of his actions and all of his rhetoric shamed the nation. But a simple U-turn is neither wise nor feasible. Biden needs to reject the cruel ideology of the anti-immigrant right, but eschew the “open borders” fantasies of many on the left. He needs to learn from Obama’s mistakes as well as Trump’s, and build new partnerships with America’s neighbors to the south.