ISIS-related events leading up to U.S. airstrikes in Syria

Monday evening, the United States and allied Arab nations launched airstrikes against ISIS targets in Syria. This marks the first time the U.S. has taken military action against ISIS in Syria. Previously, the U.S. has conducted airstrikes against ISIS in Iraq.

ISIS, the Islamic State of Iraq and Syria, traces its roots back to that al Qaeda faction, al Qaeda in Iraq. Although its origin is linked to al Qaeda, the two groups have recently had a falling out over differences between al Qaeda's leader Ayman al-Zawahiri and ISIS' leader Abu Bakr al-Baghdadi. ISIS is sometimes referred to as ISIL, the Islamic State of Iraq and the Levant, because of variations of the Arabic name.

The gallery above highlights recent events in ISIS' history leading up to the United States' airstrikes in Syria.

ABC News map highlighting ISIS-controlled area in Iraq and Syria