U.S. military officials are not saying where and when the attacks against American forces in Syria took place.

Of all the factors currently tearing the Middle East apart, none is more consequential than the war in Syria ... between the region's Sunni-majority states and Shia-majority Iran.

has been instrumental in advances against Sunni jihadists in Syria as well as in Iraq. Iran also believes Saudi Arabia is trying to destabilise Lebanon, where the Iran-backed Shia movement ...

Pakistani authorities struggle to control months of tit-for-tat attacks between Shia and Sunni tribes in tribal region.

In Syria, Iran has settled Shia families from Iraq and Lebanon in strategic Sunni areas between Damascus and the Lebanese border. Tehran has found a partner in the Alawite Islamic sect ...