While "trusted insiders" revealing classified information came after cyberattacks, they were ahead of international terrorism, the Los Angeles Times reported Wednesday.
The report said Snowden and other leakers are a threat even if they do not give information directly to foreign intelligence agencies. While some congressional representatives have accused Snowden, now in Moscow, of working with Russian intelligence, there is no proof he has done so.
"The capabilities and activities through which foreign entities -- both state and non-state actors -- seek to obtain U.S. national security information are new, more diverse and more technically sophisticated," the document says.
The report cites "non-state activists" such as WikiLeaks.
"Trusted insiders with the intent to do harm can exploit their access to compromise vast amounts of sensitive and classified information as part of a personal ideology or at the direction of a foreign government," the report states.