is this a consistent theory that simply swaps out whoever is main US opposition at the time? first Russia now China…

or is it simply a good tactic for sabotage, so employed widely?

There are 2 overarching models always working.

An Internal and external energy model.

You can power project external energy into another nation, normally those with greatest amount of external energy don’t get fucked with. 

Internal energy is the CIA, opsec, psyops, etc. 

These never go away they just move hands and/or mediums.

That’s how I view them.