The armed Islamic State (IS) group has executed dozens of members of the Syrian army they captured, after seizing an air base in the northeast of the country, a group monitoring the violence said. Al Jazeera's Rula Amin reports from the Lebanese capital Beirut. Subscribe to our channel http://bit.ly/AJSubscribe Follow us on Twitter https://twitter.com/AJEnglish Find us on Facebook https://www.facebook.com/aljazeera Check our website: http://www.aljazeera.com/