Iraq's current woes were years in the making

...

This growth is thanks, in large part, to the success that ISIS has had in Syria since 2011, when that country's civil war began. In that time, the militant group gained experience, recruits and resources as it gobbled up territory -- and, with it, millions of dollars and military firepower that has helped it to flourish.

And Ramzy Mardini, a fellow at the Atlantic Council think tank now in Jordan, says there's been a "concerted effort to merge Iraq and Syria into one sectarian theater," crediting what's happened in Syria with breathing "new life into militancy in Iraq, rejuvenating their confidence, resources and cause."