Accroding to Chinese law, airsoft BB is illegal, that might sound absurd, but it is the law. And it is selectively enforced.
There are stories that people get penalty just for selling toy guns, http://news.sina.com.cn/pl/2016-12-31/doc-ifxzczfc6640913.sh... in Chinese). It cause some discussion and debate on the internet and within the law realm, but by 2018 the supreme court gave some guidance for such case. https://www.spp.gov.cn/xwfbh/wsfbt/201803/t20180328_372604.s...
Personally I don't think it is a leverage for the trade war, the laws in China is not so mature as in US, and tend to be more tough when it involves guns.
edited for spelling error.