Due to a certain Prince in the Galactic Family, there's been a collapse between 2 realms; seedrians, aliens and mobians ALL started to discover eachother, from the cause if dimensional rifts, left by Oswald.
Seedrians and Aliens are clumped together in 1 term alltogether, though are seperate, according to both cultures. "Seedrian are a distinct, developed species, with their own galaxy and even universe, so to call them just "Aliens", as a group of unidentified and undiscovered living organisms, feels derogatory", according to Gaby, who is second-to be in charge of monitoring their species.
Charlie, being in charge of the mobians, started talking and settling with government-officials, new laws, so that aliens amd seedrians would be accepted as normal residents, though much movement hasn't happened yet. So far, aliens have no rights, so they are under endangerment to be executed fairly in self-defense for any higher-up or government-worker. If an alien is causing trouble toward Mobian individuals, the military gets involved, in disarming and disabling them, unless they are required to be terminated, due to being a public danger to society.
In other words, kaijus sometimes invade mobius. Most countries have such a developed arsenal, that kaijus tend to be exterminated, before they can destroy the entire world.