|Faction: International Space Defence Force|
|Era: Scion Campaign|
The ISDF or International Space Defence Force was a coalition force formed by the merging of the NSDF and CCA (and presumably the remains of the CRA) under Armond Braddock to defend earth from foreign threats, both alien and non-alien, after their joint defeat of the Furies. It later also saw action against the Scions.
Once it had formed, the ISDF began constructing outposts throughout the solar system, many being on the sites of old Cold War bases. The ISDF also began to push boundaries in the Solar system, building bases as far afield as Pluto and the Dark Planet.
The ISDF's first taste of conflict came during the Scion Exodus, when the test subjects of Project Pedigree fled. Under Braddock's orders, the ISDF chased the Scions from the system believing they were Furies.
By the time of the Scion Collective's return, Braddock had worked hard to keep the ISDF under as little control by the AAN as possible. He had funnelled funds from the AAN to use parts of the ISDF to establish secret outposts on Pluto and the Dark Planet, both officially out of the ISDF's reach and the latter officially undiscovered.
When the Voyager II satellite was shot down on Braddock's orders it sparked a war with the Scions that revealed Braddock's past actions. They launched attacks on bases on both Pluto and the Dark Planet, the ISDF counter-attack pursuing them through a wormhole to the Core System. There, the ISDF began to systematically eradicate Scion forces, once again under the mistaken impression that they were attempting to destroy humankind.