MOSCOW — If this article were published in a newspaper based in Russia, it could be labeled 18+ — like an X-rated movie — and start with the following disclaimer: “This article contains information not suitable for readers younger than 18 years of age, according to Russian legislation.”

Such warnings, put on any articles that discuss homosexuality or gay rights, are the result of a law nominally aimed at “protecting” children by banning “propaganda on nontraditional sexual relationships” but widely understood as an effort to suppress homosexuality and Russia’s fledgling gay rights movement.

The law, signed by President Vladimir V. Putin in June, has ignited international condemnation and blindsided the Kremlin with the sort of toxic political controversy that officials had desperately hoped to avoid ahead of the 2014 Winter Olympic Games in Sochi. The last Olympics on Russian soil, in 1980, was marred by the boycott over the Soviet invasion of Afghanistan.

The furor includes a boycott of Russian vodka in gay bars throughout the West and some calls for a boycott of the Sochi Games altogether. Beyond putting organizers on the defensive, it has cast worldwide attention on the cruel circumstances in which most gay people live in modern Russia.