So you for real think that there's enough military equipment and people trained to use it, on 1 planet, do defeat a MULTI-DIMENSIONAL empire? Haha. No. You forget that the world is hugely divided anyway, and the only real competitor would be NATO forces and such and even they would be completely obliterated. Even then, bullets and missiles don't just appear. They need to be made and sent to troops, which would be impossible. We'd run out of them without even making a dent on the Combine. Also, shut up about the F-18s and such. There's no where near enough of them to match the Combine airforce, and your understanding of air combat is completely flawed.