The spokesman of the Islamic State militant group says his fighters are ready to face a U.S.-led military coalition and is calling on Muslims worldwide to kill civilians of nations that join the fight.

Islamic State group spokesman Abu Mohammed al-Adnani says President Barack Obama’s coalition will not be able to defeat the jihadis.

Obama is currently working to form a global coalition to confront the Islamic State group, which controls large parts of Syria and Iraq.

Al-Adnani called on people in an audio released late Sunday to prevent their sons from joining rebels that the U.S. plans to train to fight the Islamic State group. He says jihadis will make them “dig their graves with their own hands and have their heads cut off.”

(AP)