The rightful president of Belarus, Svetlana Tikhanovskaya, appeared via video last month before the United Nations Human Rights Council. Her country’s August election, she declared, had been “stolen.” Despite objections from a representative of the Belarusian government, who said she had no right to address the body, Ms. Tikhanovskaya implored the United Nations to act. “Standing up for democratic principles and human rights is not interfering in internal affairs,” she insisted, “it is a universal question of human dignity.” No one knows how Donald Trump’s Covid-19 diagnosis will affect his presidential campaign, but before falling ill, he repeatedly suggested that...