According to James R. Clapper, Director of National Intelligence, the likelihood of hacker attacks will continue to grow in the short-term perspective. He notes that Russia, China, North Korea and Iran, as well as a lot of extremist groups, will be using cyber space for launching their attacks, reports BBC.

“In 2015 that number grew to about 50 arrests. These individuals were taken into custody for different reasons, the major one being attempting to assist ISIS,” Clapper siad.

According to Clapper, terrorists living in the US are particularly dangerous. He stressed that ISIS militants are continuing to urge people all over the world to join their ranks.

Clapper claims that FBI placed under arrest about a dozen of ISIS followers in 2014.