Military strategists believe cyberspace is the "fifth combat space" after land, sea, air and outer space.

Many developed countries expand great efforts to build cyber armies with advanced technologies and a substantial military budget as internet technology grows rapidly.

USA

It has the largest cyber army and was the first country to build one. United States Cyber Command (USCYBERCOM) launched in May, 2010 with 4,900 employees hired in the following years.

USCYBERCOM announced it will introduce 40 cyber teams in March, 2013 as 13 of them are confirmed as attack forces to counterattack when the nation receives major cyber attacks.

The rest of the teams will support United States Pacific Command in Hawaii and Central Command in Florida.

The 40 teams have been established before the fall of 2015. Michael Rogers, commander of the US Cyber Command, said in Sept 2015 that the number of people in the cyber army will reach 6,200 before 2016.