View Solution

The trophy description doesn't appear to exactly correct. I have seen people say any 20 air strikes, one each of all the air strikes (which means beating the entire game for the final one), some said only dropped strikes counted and artillery didn't count. I was able to pop the trophy without even unlocking the jet pilot so I could not even use bombs or missile strikes at all. I don't know exactly how many artillery I dropped but I was able to get the pop when I threw smoke so the heli would pick up a pallet of money.
My coop partner was myself on another system, I drove around and used both characters to throw the smoke to pick up strikes and cash around the game. I did use some artillery but 0 plane/jet dropped strikes like the cluster bombs or missiles.
Also as far as coop goes, the servers are technically closed but the game isn't hosted through them, however you need to accept the User Agreement to go online. I was able to use a copy of The Orange Box, try to start TF2 and it will show an agreement, accept and you will then be able to 'connect' to the server and try coop. It is still very picky about connecting to other games.