While I like the idea of events like this, I dont really like the idea of them giving you increasingly annoying negative consequences. If they want you to defend them, they should give you more money right?
Feels like it would practically force the player to do these events, because if not you'd get too much negative impact on your gameplay. Events should be optional imo, like a bonus, not something that punish the player if he doesnt manage to complete it. Fighting aliens is annoying as it is.