Secured Mode = Permanent War Protection (though you could turn it off if you desired)
On Fearless Blue, none of your countries will have Secured Mode. However, you can buy War Protection for 1 GC / country / 4 game months (1 rl day)).
On every other world, only your main country will be in Secured Mode. Every additional country will not be. Hoewever, again, you could purchase War Protection for 1GC / country / 4 game months (1 rl day in all worlds but LU where 4 game months is 16 hours).
By purchasing, I'm not sure if you're referring to buying one from another player on the Cash Market or buying a Computer Controlled Country for 100GC. If you're talking about buying a C3, I'd highly NOT recommend doing that. The cost is way too high. It's much cheaper for you to trade a few GC for Simcountry Dollars (SC), and buy some weapons and conquer the C3 instead. Even not know
K
Kaixs (Little Upsilon)
All worlds
D
Daelin (Little Upsilon)
All worlds
Btw, unless you have trillions of assets (like >$10T in cash just sitting in the country) or at least 20M people in your country, it's unlikely anyone would ever attack you. You can't sell population in a country if it has less than 21M people (and usually higher than this), and the cost to take your country (plus the damage done to the country in taking it) outweighs any gain a raider would receive afterwards.
I just don't want you having to waste GC for WP for a 12M population country.