NEW : Liang : It is Gates ' second visit to the country since he assumed the post in December 2006 . Relationship has opportunities and challenges . The trip is Gates ' second to China since he became defense secretary . The relationship between the two nations suffered a setback last year . Gates has said he wants the two countries to have more high - level visits .
NEW : Liang : Relationship has opportunities and challenges . The trip is Gates ' second to China since he became defense secretary . The relationship between the two nations suffered a setback last year . Gates has said he wants the two countries to have more high - level visits .