China seeks geopolitical space in the Western Pacific . The spearhead of China's expansion is the navy which is now the world's largest with an expanding carrier force to enforce its maritime claims in the South China Sea and elsewhere.   The geopolitical pivot for China is Southeast Asia.  In view of China's constricted maritime geography, Southeast Asia is the one place that can provide access for  its expanding navy allowing China to expand in different directions.  Control of this region would deprive the US of a positional advantage in the Western Pacific,  It would divide the Indo Pacific into two sections, the Indian Ocean and the Western Pacific., separating Japan from India and nullifying  the Quad grouping which brought together the US, Japan, Australia and India to counter Chinese expansionism. Because of its strategic value, Southeast Asia has become a key region in the rivalry between China and the US with its partners in the Quad.  However, Southeast Asia is a region of great diversity and some countries would side with China while others would resist it. Whether China can achieve control of this region is of great concern to the US and the Quad as it relates to Chinese long term ambitions and its challenge not just to the region but to the global order.