A new senior U.S. Defense Department official expressed hope Tuesday that Japan will further contribute to the bilateral security alliance by exercising its right to collective defense.

"If Japan is able to do more, I think we would, you know, be happy with that," Peter Rodman, assistant secretary of defense for international security affairs, told a news conference.

"That's for the Japanese to decide. It may well be that the new administration is tackling this question in a way that had not been tackled before," said Rodman, who met the press for the first time since assuming his post late last month.

Japan's current position is that while it has the right to collective defense under international law, this would violate Article 9 of the Constitution, which renounces the use of force as a means of settling international disputes.