I think there have been a number of structures set up to look at national security issues—the National Security and Intelligence Committee of Parliamentarians is an example—but also, in this case, the ad hoc committee structure that was struck and the panel of arbiters used a number of different techniques to ensure that information related to national security could be divulged to the maximum extent possible while still protecting what is highly sensitive information. For example, the technique of summarizing key national security information so as not to reveal sensitive information about sources and other issues has been effective in allowing content to be released in some cases while protecting the methods and sources.
On April 19th, 2024. See this statement in context.