EGYPT-LIBYA-UNREST-CHRISTIANS-IS
Mohamed El-Shahed—AFP/Getty Images
Relatives of Egyptian Coptic Christians purportedly murdered by Islamic State (IS) group militants in Libya react after hearing the news on February 16, 2015 in the village of Al-Awar in Egypt’s southern province of Minya.

Brutal killing of 21 seems an attempt to provoke retaliation

The executioner speaks in English and points his knife toward the Mediterranean. "We will conquer Rome, by Allah's permission," he says.