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The U.S. condemned the videotaped beheading of 21 Egyptian Christians kidnapped in Libya, explicitly blaming ISIS-affiliated terrorists Sunday for the "wanton killing of innocents."

The Egyptians, dressed in orange jump suits, were beheaded after being forced down on the ground on a beach. An early caption in the video says the location is "Wilayat Tarabulus by the Mediterranean Sea," which suggests that it was filmed near Tripoli.

Each of the victims, who are all male, is paired with a masked, knife-wielding terrorist and, after a brief statement by the ISIS leader, they are all beheaded.

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The video is called "A Message signed with blood to the nation of the cross" and was released by the group’s Al-Hayat Media Center, according to Flashpoint Intelligence, a global security firm and NBC News consultant.

"This undeniably means that the group now views Christian populations as not only targets but also part of the bigger 'Crusader plot,' not separate from the US-led coalition or aggressors," a Flashpoint report said. "The group's message is highly intimidating and it somewhat challenges the Western nations to intervene and save the Christians as it intervened to save the Yazidis and others."

The video appeared on the Twitter feed of a website that supports ISIS.

The U.S. statement came a few hours after Egypt's official state news agency said a Coptic Church spokesman had confirmed the killings. "This heinous act once again underscores the urgent need for a political resolution to the conflict in Libya, the continuation of which only benefits terrorist groups, including ISIL," it said.

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Ayman Mohyeldin of NBC News contributed to this report.