An ISIS affiliate in Egypt is insisting that it brought down a Russian passenger plane over Sinai Saturday, killing all 224 people on board.  The terrorist group said on the day of the crash that it brought down the airliner in response to Russian airstrikes that have killed hundreds of Muslims in Syria. 

The claim made by Sinai Province was dismissed by Russian and Egyptian officials.  Investigators say the plane is unlikely to have been struck from the outside, and they doubt the group has the technology to shoot down a jet from 30-thousand feet.  

Despite the denials by Russia and Egypt, US and UK intelligence believes that a bomb on board the plane was the cause of the crash. CNN reports that a US official said that evidence points to 'an explosive device planted in luggage or somewhere on the plane'. 

PHOTO: Getty Images