Where would this fit in the existing ICAO architecture?
Nowhere because ICAO is purely civil, and does not, by its founding convention, extend its standards and recommeded practices to military aviation.
Each State is sovereign in his own national military procedures.
The only execption are the rules of the air to intercept civil aircraft ( how to postion yourself, and how to respond, etc..)
There are no internationally agreed "rules" on wether or not to intecept an aircraft ,each State has its own regulations.