There really is practically nothing you can do..
But in the future, join an alliance.. even if you are not as active on the forums, it will give you the protection you'll need.
also, build up a warchest.. by warchest, I mean kind of like a saving money for times of war. That way you'll he able to purchase military and pay your bills daily.
Do both of these things, and your nation will become a whole lot safer in the future.
p.s. not many nations outside of yyour "alliance" will aid you in times of war. This can be for a variety of reasons, and if you wish for me to explain, then I can.
Good luck to you though!
-Universal Darkness