The Prime Minister, I think, is where the buck stops. Under him is the Minister of Public Safety, and obviously the counterterrorism strategy is something that he released, but it was done in cooperation with the Minister of Foreign Affairs, the Minister of Justice, the Minister of Transport, and so on.
In terms of the kind of binding leadership role, the Minister of Public Safety plays a big part in that, given his portfolio includes CSIS, the RCMP, and CBSA, and those are three core members of the security intelligence community.