Yes and if the aims of the project are crimes against humanity, something that would surely offend the sensibilities of any normal person, then it requires absolute secrecy and all participants who need to be looped into the know can't have any moral qualms about it or you end up with a whistle blower.

In the example I used of the Manhattan project, a sense of patriotic duty and honor was shared among the participants who maintained the secret. They all believed they were doing the best thing to effect an end to the war.