Using a computer virus, hackers in 1998 penetrated and took control of over 500 computer systems that belonged to the army, government and private sector of the United States. They also inserted malware into the computers. The whole situation was dubbed "Solar Sunrise" after the popular vulnerabilities in computers that ran on operating systems called SunSolaris. Initially, it was believed that the attacks were planned by operators in Iraq. It was later revealed that the incidents represented the work of two American teenagers from California. After the attacks, the defense department took drastic actions to prevent further incidents of this kind.