ISIS and its sympathizers have killed at least 525 civilians in six attacks over the last two months, NBC News reported.
Since October 10, the group has not gone more than three weeks without being linked to a high-profile terrorist attack.
The bloodshed has touched six countries in the last eight weeks — Turkey, Egypt, Lebanon, France, Tunisia and the US, where authorities are still trying to determine the extent of any relationship the San Berardino attackers may have had to the terrorist group.
American counterterrorism officials say that ISIS directed three of the attacks from its territory in Syria and Iraq, while the rest were organized and orchestrated by local sympathizers.
