Vice President Joe Biden and Chinese President Xi Jinping are discussing efforts to forge a new model for relations between the major powers, but they've made no public comments about a new Chinese air defense zone that's become a major friction point in Asia.

Biden appeared somber and subdued as he and Xi spoke to reporters after a meeting that ran about an hour longer than scheduled. The two planned another meeting and a working dinner Wednesday evening.

Biden says ultimately the relationship must be based on trust and a positive notion of each other's motives. He says Xi is candid and constructive and says those qualities are sorely needed.

He says the possibilities are endless if the U.S. and China can get their relationship right.