The Japanese, U.S. and Australian defense chiefs on Saturday agreed to cooperate on denuclearizing the Korean Peninsula and urge North Korea to return to disarmament negotiations that have remained at a standstill since 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. President Donald Trump and North Korean leader Kim Jong Un failed to reach a deal, Pyongyang has resumed provocative actions such as recent short-range missile tests.

Prior to the trilateral gathering, Japanese and Australian defense ministers held bilateral talks and agreed to work together to crack down on ship-to-ship smuggling involving North Korean vessels, while confirming the importance of bilateral security cooperation.

At the outset of his meeting, Iwaya told Reynolds, who took up the post late last month after the general election in May, that Japan is willing to expand joint drills with Australia to bolster their joint defensive capabilities.

North Korea is believed to use illegal ship-to-ship transfers of goods as a way to evade U.N. Security Council sanctions aimed at preventing Pyongyang from developing nuclear weapons and ballistic missiles.