HONG KONG (Reuters) -China will attempt to further boost its recent strategic diplomacy and power projection efforts as it hosts its annual security forum this week amid roiling regional tensions. Foreign diplomats and security analysts say they expect Chinese officials will use the Beijing Xiangshan Forum to push President Xi Jinping's vision of the international order he outlined earlier this month, calling for unity against "hegemonism and power politics" - a swipe at the United States. Some 1,800 representatives from 100 countries, including officials, military personnel and scholars, will attend the three-day event which opens on Wednesday, China's official Xinhua news agency reported.