A US F-16 fighter jet shot down a Turkish drone, taking out another NATO ally's aircraft over Syria

• A US F-16 fighter jet shot down a Turkish drone in Syria on Thursday. 
• The rare clash between two NATO members occurred after the drone was considered a threat to US forces in the area. 
• The Pentagon's Press Secretary called it a "regrettable incident" and said US forces had cited self-defense in the shoot down.

A US military F-16 fighter jet downed a Turkish drone operating above Syria on Thursday, marking a rare clash between Washington and a NATO ally.