Hello, I have reviewed this document as part of the security directorate's ongoing effort to review all IETF documents being processed by the IESG. These comments were written primarily for the benefit of the security area directors. Document editors and WG chairs should treat these comments just like any other last call comments. Draft-ietf-avtcore-monarch-17 as a whole provides useful advice. There are a number of editorial nits that will be provided to the authors in a separate E-mail. Unfortunately, the Security Considerations section fails to appreciate both the more nuanced view and the contradiction exhibited by the same section of RFC 3611, to which it refers. On the one hand, the measurements reported in XR blocks could be sensitive and one might wish to provide them with confidentiality. On the other hand, intermediate parties may have legitimate reasons to view the measurements, so that end-to-end encryption is not always desirable. It would be helpful for this document to discuss the trust models that might be encountered in operation, and how confidentiality and authorized usage could co-exist within these models. Of course, it may be legitimate to conclude that under some circumstances such coexistence may be impossible, and local policy may therefore be either to suppress the measurements or accept the consequences of their disclosure. Tina