Go to the road that is located between the allied base and the chinese base (you can see that place in your pda).

Wait there about 30 seconds and the allied soldier and the chinese soldier will start shooting each other, leaving you a lot of high-grade weapons such as combat rifle, bullup rifle, anti-tank rocket, fuel-air rpg, and ammo (a lot of it).

There will also be a bunch of APCs, cars, tanks, trucks, and helicopters passing by or shooting each other. You can steal those vehicles to keep or to fight a faction.

One note - if you want to survive in this crazy war, you have to be a friend with both the allies and chinese, and keep a distance!