In the rising chorus of trade groups decrying China’s stepped-up enforcement of its antitrust laws, a U.S. business organization is providing some insight into why foreign companies seem to feel besieged and confused. The U.S.-China Business Council report released Wednesday tries to unpack China’s Byzantine antimonopoly process and its proliferating probes against foreign companies The reports says a survey of the group’s members showed that more than four-fifths are at least somewhat concerned about Beijing’s enforcement of its six-year-old antimonopoly law. It said 21% of the respondents had undergone a merger review, while another 18% had been subject to an investigation into their pricing practices or other matters. The group didn’t disclose how many companies responded to the survey or when it took place. One reason behind the concern: The antimonopoly law is enforced by three agencies, each of whom oversees a different portion of it. China’s Ministry of Commerce oversees mergers and acquisitions, even of those involving companies not based in China. That agency provides a comprehensive list of its cases.