President Donald Trump is not generally the reticent type. When it comes to the fate of almost 800,000 young immigrants known as Dreamers, however, he has been unusually quiet.

Trump is under pressure from conservative state officials who are threatening to sue the federal government this week if he doesn’t end a 2012 program that enables so-called Dreamers — young undocumented immigrants who were brought to the country as children — to live, study and work in the U.S. Meanwhile, immigration restrictionists have encouraged Trump to use the lives of Dreamers as a bargaining chip to get a border wall and more aggressive policies out of a reluctant Congress.

Trump’s failure to reassure Dreamers that they won’t be arbitrarily uprooted and deported is both alarming and cruel. If the president ends the protections that have enabled hundreds of thousands to invest in themselves and contribute to their communities, it will be yet another shameful episode in a presidency that already has too many.

The moral case for Dreamers is obvious. They arrived in the U.S. as kids, not lawbreakers. Many know no other country and are American in culture and allegiance — indeed in all ways but official citizenship.

The economic case is no less compelling. America has invested in Dreamers’ educations. It has paid for the infrastructure that Dreamers have used. Why would Americans now deny Dreamers the opportunity to give back to their adopted country?

Sens. Lindsey Graham of South Carolina and Dick Durbin of Illinois have proposed the bipartisan DREAM Act of 2017 to put Dreamers on a path toward a green card and, eventually, citizenship. To qualify, applicants would have to have arrived as children and have been continuously present for at least four years before the law’s enactment. They would also have to meet education requirements and pass a criminal-background check.

There is no good reason to deny Dreamers’ participation in American life, and to deny Americans the benefits of Dreamers’ participation in the economy.

FROM AN EDITORIAL BY BLOOMBERG VIEW