China's ruling Communist Party has set in motion a controversial national security law for Hong Kong, a move being seen as a major blow to the city's freedoms. The law to ban "treason, secession, sedition and subversion" could bypass Hong Kong's lawmakers. Critics say China is breaking its promise to allow Hong Kong freedoms not seen elsewhere in China. After last year's wave of sustained and violent protests, Beijing is now attempting to push them through, arguing "law-based and forceful measures" must be taken to "prevent, stop and punish" such protests in the future. On Friday, Hong Kong's government said it would co-operate with Beijing to enact the law, adding it would not affect the city's freedoms.