The Energon Pub

Why doesn't alien terrorists or Unicron followers blow up the vector sigma to prevent the making of more autobots and decepticons so they can rely Unicron to give them sparks?

Thats what I have wondered myself. Either Vector Sigma is heavily guarded, or deep underground, or both. But in a way it would be pointless, as Vector Sigma isn't the only way to create As and Ds.

well vector sigma is pretty deep into the planet and we know that in the key to vector sigma it was gaurded but im not sure if anyone whos not from cybertron really knows bout it

Because Unicron wasn't invented when they came up with the concept of Vector Sigma, and only the Transformers really knew of Vector Sigma.