Although the United States has never perfected the practice of its principles, American leaders from both parties have long seen their country as a model worthy of emulating. The Republican presidential nominee, Donald J. Trump, departed from this view in a striking interview this week with The Times.

Mr. Trump was asked about orders from President Recep Tayyip Erdogan of Turkey to detain tens of thousands of Turkish citizens. Asked whether he would press Mr. Erdogan “to make sure the rule of law applies,” Mr. Trump did not emphasize the delicate nature of criticizing a strategically important ally. Instead, he focused inward, saying that “when it comes to civil liberties, our country has a lot of problems, and I think it’s very hard for us to get involved in other countries when we don’t know what we are doing and we can’t see straight in our own country.”

The problems he had in mind were “policemen being shot in the streets, when you have riots, when you have Ferguson. When you have Baltimore.” The United States needs “to focus on those problems,” he said.

This argument — that the United States could not be a model because of its domestic problems — was made during the early years of the Cold War, when racial segregation and violence against civil rights demonstrators generated international criticism. But this case was made by Soviet propagandists, not American presidential candidates.

During the 1957 crisis over school desegregation in Little Rock, Ark., for example, the Soviet newspaper Izvestia criticized American leaders for having “audacity to talk about ‘democracy’ and speak as supporters of ‘freedom’ ” while racist mobs barred nine African-American students from Little Rock’s Central High School. Sympathetic foreign observers expressed concern that American race discrimination undermined the ability of the United States to condemn injustice elsewhere. ...