The easy way to win the WW III on hardcore
1. Stay away from capitals! Unless you are up for punishment.
2. Only do Raid missions where you defend if possible.
3. DO NOT UPGRADE ANY UNITS!
Doing so will cause you to be promoted by default. The AI will have at least a 2 rank advantage against you! If you follow this tip the highest you will get is a Rank 2 whereas the AI will be no more than a Rank 3. Assuming you win all missions. Promotions are nice and give you some fancy firepower, but the AI gets the same firepower if not better.
4. Do Conquest missions at all times if possible:
a. Just spawn Riflemen and start grabbing uplinks until you set off Defcon. Then spawn Gunships and attack any Artillery and/or opposing riflemen/engineers.
The object is to protect you captured uplinks at all costs and keep the AI from taking any.
5. If you think you are going to lose just quit the game before it saves. When you start the game again you will be left at the exact point you left at. If not you will lose territory and will have to regain it back before you get to the last point you lost at.