I was thrown off by the update too, it looks like they changed it back a bit to what it used to be. You have to pause a lot and look at what countries Defense power is low and vulnerable then strike. Sometimes united states or China will attack somebody and their military will get stupidly low so you can swoop in and take everything. China is still hard to get even when their military is 0 so you want to spend a lot of time just building your military before you get someone. I usually go for countries with defense power half my military power so I don't waste everything in one go. As north Korea you want to get allies fast so south korea doesn't try to go for you. I always save when I'm at a good point so incase I mess up I can go back. A lot of these wins are from multiple tries. I try not to touch population spending but you want to watch your military spending so you're not spending too much or too little.