You dropped the extremism part, which always implies "anti-constitutional" in these contexts and by law.
To provide some background as an example, a member of the German Kommando Spezialkräfte (KSK) was arrested last year as a member of a right-wing terrorist group that planned to overthrow the government. That's just an example, there are many more.
Now do everyone a favor and stop commenting on articles you obviously haven't read, especially when you display not the slightest knowledge of the context.