From Aron: "While it has singled out the royal family in its public and written discourse, in tangible operational terms, the Islamic State has concentrated its efforts on attacking and killing Shi`a in Eastern Province. As its campaign continues to escalate, the Islamic State may eventually leverage the sizeable pool of Saudi volunteers who have traveled to major jihadist battlefields such as Iraq and Syria. Just as important, Saudi foreign fighters have distinguished themselves on the battlefield in positions of leadership as well as a wellspring of suicide bombers.[29] While reliable estimates of the numbers of Saudis who may have returned to the kingdom are difficult to pinpoint, there is a wide body of evidence to suggest that Saudis are among the most widely represented foreign fighter cohorts in Syria and Iraq.[t] The potential return of battle-hardened and tactically proficient fighters to the kingdom from warzones such as Syria and Iraq, regardless of their prior organizational affiliations, enhances the Islamic State’s potential recruiting pool. The return of Saudi volunteers who traveled to Iraq to join the insurgency against the United States were integral to al-Qa`ida in the Arabian Peninsula’s 2003-2006 campaign against the kingdom.[30] Saudi Arabia will likely be confronted with a similar challenge down the line."