The Japanese, U.S. and Australian defense chiefs urged North Korea on Saturday to return to denuclearization negotiations that have been at a standstill following the collapse of a second summit between Washington and Pyongyang in late February.Acting U.S. Defense Secretary Patrick Shanahan reached the agreement with Japanese and Australian defense ministers Takeshi Iwaya and Linda Reynolds at their meeting on the sidelines of the Asia Security Summit, known as the Shangri-La Dialogue, in Singapore.In the wake of the collapse of the Feb. 27 to 28 summit in the Vietnamese capital, where U.S.…READ FULL ARTICLE