What they had done was view extremist material widely available on the internet.
From the voanews.com
In addition, he said, Canada now has more Islamist extremist groups than Mexico.
From the thenewstribune.com
He said extremist groups use the Web more as a marketing and communication tool.
From the cnn.com
The country has been engaged in a long battle against militant extremist groups.
From the suntimes.com
I would consider being against illegal stuff to be the least extremist position.
From the economist.com
Most right wing extremist don't know the difference between a Sikh and a Muslim.
From the nation.time.com
What we need to be clear about is, our enemy has an extremist political ideology.
From the washingtontimes.com
Several officially banned extremist groups operate more or less openly in Punjab.
From the kentucky.com
So extremist defenders of the free market have found themselves an easier target.
From the edition.cnn.com
More examples
A person who holds extreme views
(used of opinions and actions) far beyond the norm; "extremist political views"; "radical opinions on education"; "an ultra conservative"
(extremism) any political theory favoring immoderate uncompromising policies
The Extremist is an instrumental rock album released by Joe Satriani in 1992 and re-released in 1997 with his entire Epic Records catalog.
The Extremist was a four-issue comic book mini-series, written by Peter Milligan with art by Ted McKeever. The series was published by DC Comics through their Vertigo comics imprint from September to December 1993. ...
Extremism is a term used to describe the actions or ideologies of individuals or groups outside the perceived political center of a society; or otherwise claimed to violate common moral standards. ...
(The Extremists (comics)) The Extremists are a team of supervillains in DC Comics Justice League titles, they were introduced in Justice League Europe issue #15.
(extremism) extreme ideas or actions
(Extremists) term briefly used by WWE to refer to its ECW brand wrestlers to emphasize that they, and the ECW brand, are more "extreme" in comparison to the Raw and SmackDown! superstars.