The "Karn" had been visiting our planet for a long time. They considered it a prime mining resource. The hominid inhabitants were at best a "sideshow attraction" But we began to threaten their resource with our technology, so they used it against us. They crippled what little infrastructure we had not already neglected and left to decay. They even "hacked" our drones and used them to mop up the insurgency. Now they were in for a few surprises they had not anticipated... Suggested listening : Emerson Lake & Palmer "Brain Salad Surgery"