Since 2004, the economic rise of both China and India has also helped forge closer relations between the two. Sino-Indian trade reached US$36 billion in 2007, making China the single largest trading partner of India. The increasing economic reliance between India and China has also brought the two nations closer politically, with both India and China eager to resolve their boundary dispute. They have also collaborated on several issues ranging from WTO's Doha round in 2008 to regional free trade agreement. Similar to Indo-US nuclear deal, India and China have also agreed to cooperate in the field of civilian nuclear energy. However, China's economic interests have clashed with those of India. Both the countries are the largest Asian investors in Africa and have competed for control over its large natural resources.