Think tanks are organizations funded and founded on a believe, whatever that might be. Their goal is to support the believe with "research." I am one that thinks that it's possible to put just about any believe in positive light. Given this then think tanks are propaganda machines. It comes down to this. If I believe in the think tank's vision then the research papers are research. If I don't then they are research with a spin. Which is the same as propaganda.

Bottom line, think tanks are propaganda machines. It just depends on what your believes are.