I was thinking about the possible propoganda benefits of a terror cell claiming responsibility for an attack that someone else committed, before anyone knew differently, or claiming they caused some sort of accident to make themselves seem stronger than they are. I know that False Flag attacks have happened before, but I was wondering if the reverse had happened?
Unfortunately all of the examples I can think of would break the 20 year rule, but the answer is "Yes" it happens all the time. https://newrepublic.com/article/92532/what-ansar-al-jihad-al-alami