Endgame Texts/Debt Loss
You've gone too far into debt. There is no one left willing to pick up the massive bills you've racked up. Dissatisfied by your poor financial management, the UN has decided to remove you from command and subsequently disbands the PHALANX project as an effective task force.
No further attempts at global cooperation are made. Earth's nations each try to stand alone against the aliens, and eventually fall one by one.