China's warning is related with US randomly violence, gun shooting, robbery etc (if you understand Chinese: http://www.china-embassy.org/chn/lszj/zytz/t1597786.htm). US and China are very different countries, like in China, the downtown of metropolis is very safe at night, but in US is totally different. And also, gun shooting in US is really normal, but extremely rare in China.
This reads like an faq for people coming to US. First item reminds people to buy travel/health insurance. Second item warns against going out alone in late night. Etc. I didn't see anything political in it.