BEIRUT (AP) — The U.S. and its allies are trying to hammer out a coalition to push back the Islamic State group in Iraq. But any serious attempt to destroy the militants or even seriously degrade their capabilities means targeting their infrastructure in Syria.

That, however, is far more complicated. If it launches airstrikes against the group in Syria, the U.S. runs the risk of unintentionally strengthening the hand of President Bashar Assad, whose removal the West has actively sought the past three years. Uprooting the Islamic State group, which has seized roughly a third of Syria and Iraq, may potentially open the way for the Syrian army to fill the vacuum.