China wants to develop what it sees as key industries by giving Chinese companies a leg up in both the Chinese and global market. Its trading partners don’t want to see their firms placed at a disadvantage, and in several cases have challenged Chinese policies. China is challenging them right back, arguing that those countries do the same thing, and that people who live in protectionist glass houses shouldn’t throw stones. If they do, China can match them “tit for tat.” (A similar battle involving cross-accusations and threats between the EU and China began unfolding this week — you can read about it here).
There’s a critical difference, though, between China and its trade partners. They all may both have policies that can be called protectionist, but they come from different starting points. In the U.S., trade restrictions and subsidies tend to be the exception to the rule, and when they do occur, are usually transparent. There’s a public approval process and an overt policy that can be challenged at WTO. In China, restrictions and subsidies are pervasive, due to the large state role in the economy, and often hard to pin down.