They have to be condenmed as the actions are clearly forbidden. Who is behind it, does not justify the action. The lack of condemnation and such free allowance of terrorist groups to operate under Islam is precisely the reason why kafirs can take advantage of it and easily blame Muslims. We will never know whos behind it. The Muslims of Nigeria are better source of knowledge then New York Times. Another point I want to make is that, all groups who operate in a hidden manner should be rejected. The Prophet(pbuh) nor the companions operated as hidden shadowy people. We don't know who exactly is behind this plenty of hidden groups, which could be enemys of Islam playing games to hatch plots. So this danger should be enough to reject them outright as defult view and only listen to them if the come out in public view and clarify their associations and backgrounds and intentions. Wasalam