The worst part about false flags is that once you are caught in the act, and you are notorious for committing them, any party can stage a false flag against your country and then suddenly your nation is paying for something it didn't do, and you have no credibility when you try to deny it.
For example, an intelligence agency from here might stage a terrorist attack, and kill Americans, to make it look like another country did it. This is to gin up a call for war, as we saw in Iraq. What happens, though, when another country stages a false flag to pit you against a stronger enemy to make it look like a bungled false flag from your agencies, the CIA in particular?
What if a third party made it look like your country tried to stage a false flag in China or Russia to provoke them against each other, or NATO? What happens then? You have a couple of world powers out for blood to target your nation, unless they have a solid intelligence apparatus to stop it.
It wouldn't even be difficult for some knuckle-head to pull off, here or there, and all plausible deniability is long gone, no matter how centralized our media or if the responsible party is a state, or private party.
Look at the events in Riverside. This "ISIS attack" happened on the day the Russians released irrefutable evidence of Turkish collusion with ISIS, which in turn implicates US officials. On the one hand you will terrorize some Americans and inflame Islamophobia and Rupert Murdoch's gang is salivating all over this, but on the other hand, the wary can now say this about Republicans and Democrats alike: "look what you have brought to our shores, and now we know you are working with ISIS. Why didn't you take out their tankers? Why would you task our soldiers to kill ISIS, but then prevent them from disarming or removing their money supply?"
CIA-NATO's Greatest Hits, False Flags Declassified