Yet, the consequences of Mr. Trump’s raw racism are not contained within America’s shores. They ricochet around the world as far away as New Zealand, poison the international climate and undermine America’s ability to secure our global interests.

Our closest allies — from Canada to Britain and Germany — expressed outrage at Mr. Trump’s demand that four members of Congress, each American citizens and women of color, “go back” to “the totally broken and crime infested places from which they came.” That allied leaders, whose countries’ partnership we prize because they share both our interests and our values, felt compelled to condemn the president’s racist comments marks a fresh nadir in global regard for America’s leadership.

When the president of the United States reveals himself to be an unabashed bigot, attacking minorities in his own country, America’s ability to stand credibly against human rights abuses, especially repression of minorities in other countries — from the Uighurs in China to Shiites in Bahrain and Christians throughout the Middle East — is thwarted in ways lasting and immeasurable. Dictators around the world encounter no opprobrium from our government and are comforted to find a fellow traveler in rhetoric and policies that demean his own people.

In case anyone needs reminding: A majority of the world is populated by what we Americans call “people of color.” To fight terrorism or prevent the spread of pandemic disease, to stem weapons proliferation or organized criminal organizations, to address climate change or punish outlaw states, we need the willing cooperation of nations around the world. None of these transnational security challenges can be combated effectively by the United States alone.

With the president increasingly alienating our allies and insulting potential partners as “shithole” countries, America is hardly well positioned to call upon the good will and cooperation of other states when next we need it most. Moreover, in our intensified competition with China for influence in Asia and markets globally, we are hobbled by the contrast between a president who embraces white nationalist mantras and holds people around the world in disdain, and China, which is still perceived by many developing countries as more sympathetic to the world’s underdogs despite its autocratic government.