PJ,
I work in the international environment where there are a small number of senior ranks doing what we refer to as Defence Engagement (previously Defence Diplomacy). A lot of it is about meetings in smoked-filled rooms; sidebar discussions with senior foreign diplomats as the trays of Ferrero Roche are passed about; exhausted spouses of said senior officers hosting yet more dinner parties to facilitate protection of British interests and National Security. You may snigger at it but I suggest you watch the Mitchell and Webb gem 'The Ambassadors' to see what I mean.
Now of course we could replace these senior Admirals, Generals and Air Marshals (and there is only a handful) and their long-suffering wives with young contractors - mercenaries if you like. Firstly, they wouldn't be accredited as Diplomats; secondly they would have absolutely no traction with the local cognoscenti; thirdly they would not deliver any Joint Effect.
But I'm sure you'd enjoy debating the point in the 6th Form Common Room.