AT&T has become the first major advertiser to come out against a measure outlawing “homosexual propaganda” that has led to protests aimed at the Winter Olympics in Sochi, Russia, as well as the first to urge “others involved with the Olympic Games” to do the same.

AT&T’s decision, expressed in strong, unequivocal language, was made known on Tuesday through a post on a company blog. “We stand against Russia’s anti-L.G.B.T. law,” the post said, using shorthand for lesbian, gay, bisexual and transgender. “Russia’s law is harmful to L.G.B.T. individuals and families, and it’s harmful to a diverse society.”

While a notable first, it is not the milestone that the protesters had sought. They have been targeting 10 giant sponsors of the International Olympic Committee to join them in condemning the law. Those sponsors, which pay for the rights to affiliate with the Olympics around the world, include Coca-Cola, General Electric, McDonald’s, Procter & Gamble, Samsung and Visa — but not AT&T, which is a sponsor of the United States Olympic Committee.

AT&T acknowledged that in its post, then stated that as a sponsor of the United States Olympic movement since 1984, the company had “showcased American athletes and celebrated their diversity all around the world.”