As we know there is this black stone in Mecca that is WORSHIPPED by millions of pilgrims every year during Hajj. They regard the stone holy and go around it chanting prayers like the ancient Hindus.
The ISIL (Islamic State) regards all sorts of STONE OR BRICK STRUCTURES anti Islamic (KUFFR).
So by logic they would wish to do to the BLACK STONE in Mecca what they did to the temples in India, Buddha statues in Afghanistan and the ancient ruins in Irak.
The Saudis must be the most worried dynasty on earth today.