Ahead of US President Barack Obama's visit to India beginning Saturday, a prominent US think tank has said that the two countries would build their strong bilateral defence ties based on the new strategic realities of Asia. The Washington-based think tank, the National Bureau of Asian Research said in a report, the defence relationship is one of the many bright spots in the overall bilateral relationship. It said, US and Indian armed forces will operate together more frequently, and US equipment will be purchased in larger quantities by India, in part reflecting the new strategic realities of Asia and a strengthened US-Indian relationship. It noted that apart from the bilateral security issues, there are differentiated security challenges each country faces in managing complex security relationships with Pakistan and China. The report said, while China looms large in Indian strategic thinking and defence planning, Pakistan continues to represent the greatest near-term military challenge to India, both in conventional ways and in its use of proxy insurgents.