Beijing's decision to impose a long-delayed security law on Hong Kong reflects the mainland’s growing concern with challenges to national unity ahead of next year's 100th anniversary of the Chinese Communist Party. But it is more immediately driven by the rising violence in Hong Kong and the political evolution in Taiwan. Despite international criticism, China will strengthen efforts to fully integrate Hong Kong and to further isolate Taiwan internationally. The issues of Hong Kong and Taiwan are intimately linked for Beijing. Hong Kong was intended to be a model of effective unification under one country, two systems, to entice Taiwan to rejoin the motherland and bring to fruition the post-World War II rebuilding of China. But Hong Kong's integration has grown increasingly fractious over the past decade, and this has reinforced sentiment in Taiwan that reintegration with China would see a similar erosion of Taiwan's political and social structures.