Defense Minister Takeshi Iwaya and acting U.S. Defense Secretary Patrick Shanahan agreed Wednesday to cooperate in new domains of warfare like outer space and cyberspace in a veiled response to China's quest for military supremacy in such areas.

Iwaya and Shanahan also affirmed full enforcement of U.N. sanctions on North Korea as a way of compelling it to abandon nuclear weapons and ballistic missiles, the Japanese minister told reporters after their meeting at the Pentagon.

They agreed that deterrence by the two countries plus South Korea is "indispensable" for the security of the region despite ties between Tokyo and Seoul souring over an alleged radar lock-on incident involving a South Korean warship and a Japanese plane.