Complex sentence: In 2002, Cirio's first international action was called Anti-NATO Day, as an act of Hacktivism he staged a virtual sit-in (DDoS attack) in the NATO website through a Flash Player script.
Split into simpler sentences: In 2002, Cirio's first international action was called Anti-NATO Day. As an act of Hacktivism he staged a virtual sit-in (DDoS attack) in the NATO website through a Flash Player script.