Here is a tip to murder your online foes' armies.
If you are the US, build 3 Tomahawk Launchers, and 2 humvees. Also train 6 rangers.
Put 3 rangers in one humvee, and the other 3 in one humvee.Send out your squad to your opponents base. If you are facing the US, make your T-launchers fire at the Patriot Missile till it is destroyed, then 2 or 3 rangers pop out.
Use your humvees to kill them. Repeat this process on the US base defenses to make your opponents defenseless. If they have any vehicles use your t-launchers to eliminate them.
If you purchase the Capture Building upgrade, you can release your rangers to capture the enemy's structures.
(china tips for base defenses will come soon.)