Pussy Riot members Maria Alyokhina and Nadya Tolokonnikova have become emblems of Russia's war on human rights and free speech: The two were jailed for 21 months for a protest-performance in a Moscow cathedral in March 20012. Since their release in December, though, they've only turned up the volume on their dissent: On Wednesday they were the guests of honor at "Bringing Human Rights Home," a concert sponsored by Amnesty International that's being billed as Pussy Riot's official welcome to America.

[caption id="attachment_141686" align="alignright" width="311"] Imagine Dragons on the red carpet[/caption]

This was no drum circle or guitar around a firepit, though: Imagine Dragons, Tegan and Sara, Flaming Lips, the Fray, Blondie and Lauryn Hill took the stage at Brooklyn's Barclays Center.

In the video above, Madonna introduces Tolokonnikova and Alyokhina to the crowd. The pop icon publicly supported the pair while they were incarcerated, and even took to scrawling "Free Pussy Riot" on her body during concerts.

Related: Lady Gaga Wants Boycott Of Sochi Olympics: “How Can We Reward Them?”

"I am honored to introduce my fellow freedom fighters Masha and Nadya from Pussy Riot," Madonna said in a statement. "I have admired their courage and have long supported their commitment and the sacrifices they have made in the name of freedom of expression and human rights."

In addition to raising awareness through the "Bringing Human Rights Home" tour, Alyokhina and Tolokonnikova are leading a petition urging Vladimir Putin to repeal some of the draconian measures passed in Russia in the past few years, including the gay-propaganda ban, a prohibition against "insulting the feelings of religious believers" and increased censorship on the Web.

"Because free thought, right now, migrates to the Internet, the state has set out to control its activity," said Tolokonnikova. "They've started to create blacklists of bloggers and Internet sites and try to restrict and control what is happening on the Internet as well."