It's time for the United States to hold Iran accountable.

Iran has executed a 21-year-old man who was arrested at age 15, Amnesty International and an Iranian news agency reported.

Alireza Tajiki was executed on August 10, the London-based human rights group Amnesty said, calling it a "shameful act."

"By going ahead with this execution in defiance of their obligations under international law, and despite huge public and international opposition, the Iranian authorities have again cruelly demonstrated their complete disdain for children’s rights," Amnesty's deputy director for the Middle East and North Africa, Magdalena Mughrabi, said in a statement.

"This shameful act marks a critical turning point for Iran, and exposes the hollowness of the authorities’ claims to have a genuine juvenile justice system," she said.

According to Amnesty, Tajiki was arrested in May 2012, when he was 15 years old, and sentenced to death in April 2013 after a criminal court in the southern Fars Province had convicted him of murder and forced male-male intercourse. It said the trial was "grossly unfair" and that the case hinged largely on confessions that Tajiki "said were extracted through torture, including severe beatings, floggings, and suspension by the arms and feet."

The semiofficial Iranian news agency Ana.ir quoted the chief prosecutor in the city of Shiraz, Ali Salehi, as saying the prosecution of Tajiki was "fair and just, and that his execution was "legal." He was quoted as saying that Iran's Supreme Court upheld the death sentence following an appeal and that Tajiki was executed in the morning on August 10.

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