SINGAPORE: Asia’s largest annual security forum opens on Friday in Singapore with territorial disputes in the South China Sea, North Korea’s military provocations and Islamist extremism expected to dominate discussions. The Shangri-La Dialogue, organized by the London-based International Institute for Strategic Studies (IISS), is to be attended by at least 20 defense ministers led by Pentagon chief Ashton Carter, IISS Asia executive director Tim Huxley said. Beijing’s claim to nearly the entire South China Sea has angered Southeast Asian neighbors and pitted it against the United States, which has conducted patrols near Chinese-held islands to press for freedom of navigation. The contested waters encompass key global shipping lanes. The Philippines, Brunei, Malaysia and Vietnam have competing claims in the area, which is believed to have significant oil and gas deposits.