Passed just six months before Russia is slated to host the 2014 Winter Olympics in Sochi, the law also allows foreigners to be arrested and detained for up to two weeks should they choose to "propagandize" homosexuality while visiting. As if the message wasn't clear enough, Mr. Putin signed another anti-gay measure at the beginning of July, this one preventing the adoption of Russian-born children by any person living in a country in which same-sex marriage is legal, regardless of that person's sexuality.
In the contest for the most medieval level of intolerance, the Russian Federation is giving Saudi Arabia a run for its money.
While Russia and the Soviet Union before it have generally been hostile to gay people, the recent intensity of Mr. Putin's war is part and parcel of his lapse into xenophobia, religious chauvinism and general intolerance as the urban middle class increasingly questions the legitimacy of his authoritarian rule.
But if Mr. Putin believed that persecution of gay people would be a domestic issue of little interest to the world, he miscalculated. As Mr. Obama rightly highlighted, the dignity with which gays are treated has been recognized as a fundamental human rights concern in much of the world. No country, especially not one on the cusp of hosting the Olympic Games, should expect such bigotry to go unnoticed.
Mr. Obama, speaking on the eve of his cancellation of a summit meeting in Moscow, said he felt Mr. Putin would surely understand "that for most of the countries that participate in the Olympics, we wouldn't tolerate gays and lesbians being treated differently." The International Olympic Committee should understand that as well. On Wednesday the committee received a petition with more than 300,000 signatures urging it to boycott Sochi as the host city.
That may be unlikely, but the IOC will have to take some definitive stand in the weeks ahead, especially after Vitaly L. Mutko, Russia's minister of sports, pronounced that Olympic athletes of all nationalities would be subject to the "propaganda" law.
Those words stand in contrast to the IOC's commitment that "the Games themselves should be open to all, free of discrimination, and that applies to spectators, officials, media and of course athletes." The Olympic spirit is not compatible with a gag order on expressions of human freedom.