Calm down bro, there are a lot of things China can do, and in reality she will be doing, as I've said in another thread...
- donate some special "humanitarian aid" to "Ta1iban", which will make USA soldiers work harder...
- veto some sanctions on certain middle-east country to show unhappiness...
- grab some resources in USA's backyard - south America, take over a few energy/mining companies...
- restrict rare-earth mineral export which makes essential parts of missiles and satellites, China has 97% of the world’s supply anyway...
- influence certain central Asia countries to close off US bases, reduce its sphere of influence...
- sell the US treasury bonds and depreciates the currency RMB Yuan, which surely will drive Dow Jones Indexes plunging, rub salts on wounds for a shaky economy is far worse than disposing a few hundred soldiers, instead hundreds of millions will get affected in that way.