Rob Joyce, head of the NSA Cybersecurity Directorate, said "what we know is often not sensitive, it is how we know it."

Researchers with Symantec said the group that it has tracked for years has recently targeted government networks in the U.S. and Middle East.

The botnet was being assembled by Russia's foreign intelligence agency, the GRU, Attorney General Merrick Garland said at a news conference.

The new role will play a key part in coordinating the government response to major hacks and other cybersecurity threats.