An al-Qaida offshoot's major offensive this week shows that the battle lines — and the motives of the various sides in the Iraq and Syria upheavals — have effectively merged. This is one conflict, engulfing the oil-producing heart of the Arab Middle East.
This week, the Islamic State of Iraq and the Levant (ISIS) seized control of Mosul, Iraq's second-largest city and a major infrastructural hub. Mosul is home to the country's most important dam and is close to Iraq's northern oil fields. ISIS has also launched offensives against Tikrit, Saddam Hussein's hometown, and Samarra, the site of a major Shiite shrine. The group nearly has Baghdad encircled.