Premier Li Keqiang of China said on Sunday that the government was failing to satisfy public demands to stanch pollution and would impose heavier punishments to cut the toxic smog that was the subject of a popular documentary belatedly banned by censors. The premier’s news conference at the end of the annual full meeting of the National People’s Congress has become a fixture of the Chinese political calendar, cast as a show of political candor and accountability. But the briefings have mostly become a stilted ritual, with questions generally preselected and massaged to avoid the airing of controversies about legal rights, corruption scandals and other themes unwelcome by Communist Party leaders. This year’s conference was no different. But Mr. Li took one reporter’s question about air pollution, which mentioned the banned documentary, “Under the Dome,” and he acknowledged that there was a gap between the government’s efforts […]