Japanese officials struggled to explain why it took them a month to disclose large-scale leakage of radioactivity from a crippled nuclear power plant after a disastrous mid-March earthquake and tsunami. The government increased its rating of the severity of the Fukushima nuclear accident from 5 to 7, the worst on an international scale. Since the quake, Japanese authorities have been consistently suspected of incompetent data analysis and blocking release of information to avoid alarming the public.