Russia's military intervention in Syria has jolted NATO and provoked frustration in Washington. On Wednesday, Russia launched cruise missiles from warships in the Caspian Sea.
Russian jets have twice entered Turkish airspace, according to NATO, which has disputed Russia's account of an accidental incursion during action in Syria.
Under Sheikh Nasrallah, Hezbollah rode to the defense of its ally Syria. But the Shiite group that was founded to confront Israel is paying a high price in lives and prestige.
Russian officials say Syrian President Bashar al-Assad is crucial to fighting the Islamic State, while President Obama has called on the embattled leader to step aside.
Survey of defectors' stories finds common themes, including opposition to brutality, corruption, and the Islamic State's preoccupation with its Sunni jihadi rivals.