Much of the current foreign policy is based on the concept of "China's peaceful development". Nonetheless, crises in relations with foreign countries have occurred at various times in its recent history, particularly with the United States; e.g., the U.S. bombing of the Chinese embassy in Belgrade during the Kosovo conflict in May 1999 and the Hainan Island incident in April 2001. China's foreign relations with many Western nations suffered for a time following the Tiananmen Square protests of 1989. A much troubled foreign relationship is that between China and Japan, which has been strained at times by Japan's refusal to acknowledge its wartime past to the satisfaction of the PRC, such as revisionistic comments made by prominent Japanese officials, and insufficient details given to the Nanjing Massacre and other atrocities committed during World War II in Japanese history textbooks. Another point of conflict between the two countries is the frequent visits by Japanese government officials to the Yasukuni Shrine, which honours not only Japanese World War II dead but also many convicted World War II war criminals, including 14 Class A convictions.