Manipulate the information flow and you can pretty much convince anyone of anything.
That's really the whole point of agent, isn't it?
You're not tough. You're not an all powerful demi-god.
But you control who knows what. And that's more powerful than a lightsaber being wielded by someone with Force leap.
Look at Issen 4 as an example. The reason the war gets started is because there's a Republic base, they surrender to the Imperials, then you wander in (pursing Hunter, based on some intelligence W2/Keeper has gathered), and they are all found massacred. (Hunter's doing, again.)
Totally makes sense from the Republic's POV to base a war on this. Some innocent colonists surrender and are massacred by an agent of the Empire.
The Empire, of course, is furious because, from their POV, a rogue SIS agent pretty much arranged the whole thing to make them look bad.
You're both played.
(And this may happen in other storylines. For instance, the cold war starts to heat up for all classes in Chapter 2. Why? All kinds of reasons, depending on class. But some of that mysterious information both sides keep getting as to where the key targets are, etc. may be being slipped to them by the Star Cabal.)
That's the point of the Star Cabal. They keep pulling strings until everyone is killing everyone.
(And the only reason that they haven't already pulled this off, according to the game, is that they haven't really wanted to. Up until some time in the recent past, they've just tried to prevent either the Jedi or Sith from getting too powerful. It was only lately that they decided "let's kill them all". And that took some prep work, which is only approved 6 months prior to the start of Chapter 3.)