Mr. Trump’s shameful defense of the white nationalists and neo-Nazis who unleashed hatred and violence in Charlottesville, Va., further abnegated America’s moral leadership. Not since the Jim Crow era has an American president so misunderstood and misrepresented our values.

Most recently, the Trump administration’s order to rescind Deferred Action for Childhood Arrivals — punishing young people brought to this country by their parents, many of whom know no home but the United States — betrays an unnecessary cruelty that further undermines America’s standing in the world.

When Secretary of State Rex W. Tillerson said that it was important to “understand the difference between policy and values,” he wrote off the very thing that makes the United States exceptional. And at a time when democratic values are under siege around the globe — from populist attacks that undermine confidence in democratic institutions to leaders who try to bolster their power by closing the space for civil society and rolling back citizens’ rights — the world cannot afford to have America cede the field to illiberalism and intolerance.

Placing American democratic values back at the center of our foreign policy does not mean we should impose our principles abroad or refuse to talk with nations whose policies run counter to them. There will always be times when keeping Americans safe requires working with those whom we find distasteful. But even when we must make those hard choices, we can never forget who we are and the future we seek.

Image The United States must be a bulwark for global democracy or powers like Russia will bully and divide, argues former Vice President Joe Biden. The Statue of Liberty, a beacon of American democracy, has welcomed millions of immigrants and refugees to the country. Credit... Keith Meyers/The New York Times

Reclaiming our values starts with standing up for them at home — inclusivity, tolerance, diversity, respect for the rule of law, freedom of speech, freedom of the press. If these are the democratic principles we wish to see around the world, America must be the first to model them.

These are also the values that tie us to our closest allies — the friends we depend on to address major global challenges. They must believe that the United States will continue to support them and to stand up for democracy.