Usually when they come to the conclusion that there is an issue related to the security of Canada, it would be as a result of doing some analysis. It would probably not necessarily be from a single source of information coming to them, but maybe from their ability to put together various sources of information and say there would be an issue here. Then they would have to look at whether or not it meets two tests.
In the first instance, they have to say that there are reasonable grounds to suspect the information would be relevant to threats of Canada as defined under the CSIS Act.
Secondly, they would also have to have reasonable grounds to suspect that the information would relate to threats to the Department of National Defence or the Canadian Armed Forces.