A new message purporting to come from an ISIS spokesman called on followers to launch attacks on the United States and Europe during the Islamic holy month of Ramadan, which begins in early June.
"Ramadan, the month of conquest and jihad. Get prepared, be ready ... to make it a month of calamity everywhere for the non-believers ... especially for the fighters and supporters of the caliphate in Europe and America," said the message, suggesting attacks on military and civilian targets.
The authenticity of the audio clip, purporting to be from Abu Muhammad al-Adnani and distributed on Saturday by Twitter accounts that usually publish ISIS statements, could not be verified.
"The smallest action you do in their heartland is better and more enduring to us than what you would if you were with us. If one of you hoped to reach the Islamic State, we wish we were in your place to punish the Crusaders day and night," Adnani said.