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. 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 Tokyo is willing to expand joint drills with Canberra to bolster defense capacities with each other.

Illegal ship-to-ship transfers of goods are activities believed to be used by North Korea to evade U.N. Security Council sanctions aimed at preventing Pyongyang from developing nuclear weapons and ballistic missiles.