LONDON, March 13 (Reuters) - Britain approved a sharp increase in exports of submarine parts and technology last year to Taiwan as it upgrades its naval forces, a move that could impact British ties with China. British Prime Minister Rishi Sunak, in a foreword to the policy document, specifically identified China’s more aggressive stance in the South China Sea and the Taiwan Strait as among issues “threatening to create a world defined by danger, disorder and division – and an international order more favourable to authoritarianism. One of the former British officials said: "Every decision around Taiwan is made very deliberately and usually cautiously