embassy?
US Customs?
http://www.cdc.gov/ncidod/dq/animal.htmCats
Pet cats are subject to inspection at ports of entry for evidence of infectious diseases that can be transmitted to humans. If a cat appears to be ill, further examination by a licensed veterinarian might be required. There is no rabies vaccination requirement for cats. Following entry into the United States, all cats are subject to state and local vaccination requirements. All pet cats arriving in the state of Hawaii and the territory of Guam, even from the U.S. mainland, are subject to locally imposed quarantine requirements.
I know some animals being brought into US from some countries are just passed through with no quarantine. Don't know if China is on that list.
Make sure you have vet records regarding shots and all of that for each of the cats