However, China's opposition to the bid of two of its important neighbors—India and Japan—to become permanent members of the United Nations Security Council has proved to be an irritant in their respective relationships. Japan, with its large economic and cultural influences in Asia, is seen by China as its most formidable opponent and partner in regional diplomacy. The two sides established diplomatic relations in 1972, and Japanese investment in China was important in the early years of China's economic reforms and ever since.