Definition: In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].
Input: (CNN) Since the headline-grabbing murder of American journalist James Foley by ISIS militants in August 2014, the world has been regularly confronted with a modern form of an ancient, horrifying method of execution. British and American aid workers, Japanese and American journalists, Kurdish and Syrian soldiers, Egyptian and Ethiopian Christians and an alleged Russian spy were among those who followed in Foley's wake: their gruesome beheadings documented on camera and disseminated as propaganda to a global online audience. Canadian John Ridsdel, held by the Philippines-based, ISIS-allied jihadist group Abu Sayyaf since he was abducted in September, is the latest victim to be murdered in this way.The wave of jihadist beheadings in recent years has horrified people all over the worldIt may have contributed to beheading incidents by non-jihadists, says academicAcademic says exposure to the videos could help "prime" some people to emulate them 
 Question:The highly ritualized killings have galvanized international opposition to _, but may also have helped attract a wave of foreign recruits to the group's cause.

ISIS