Not All Terrorists Want to Claim Responsibility for Attacks

Why would right-wing terrorists decide not to claim responsibility for their crimes? In Germany, there has been an ongoing public debate as to whether radical-right terrorists take responsibility for their crimes, particularly after the radical-right terrorist group Nationalsozialistischer Untergrund (the National Socialist Underground, NSU) was uncovered. This group did not claim credit for its attacks before 2011, when its existence was revealed.