"We will continue to implement all U.N. Security Council resolutions on North Korea".
Defence ministers of the US and South Korea attending the Shangri-La Dialogue have thanked Singapore for agreeing to host the upcoming summit.
Hours earlier, President Donald Trump met with Kim Yong-chol, a top North Korean official, at the White House.
Trump and Kim have been supposed to meet in a summit in Singapore on June 12.
The paper called the RIMPAC "a product of the Cold War" that has been held with a objective of forming a blockade around a sovereign state such as North Korea; adding dialogue and confrontation, and peace and war exercises can never go hand-in-hand.
Defense Secretary Jim Mattis is warning it will be a "bumpy road" to the nuclear negotiations with North Korea later this month. The main stumbling block is likely to be the concept of "denuclearisation" - both sides say they are in favour of it, but there is a yawning gap between their definitions.More news: Fashion Designer Kate Spade Has Died
After the meeting, Onodera told reporters the three "agreed to closely cooperate to compel North Korea to take concrete steps" in a complete, verifiable and irreversible manner.
Asked about whether South Korea and the U.S. will scale down or cancel the Ulchi Freedom Guardian drills, the deputy spokesman for the Seoul ministry said no discussion nor review has been made. "Pyongyang will get assistance only when you demonstrate in a verifiable and irreversible steps to denuclearize", said Mattis, opening the meeting with the South Korean and Japanese colleagues, gathered in Singapore to prepare for the summit.
Meanwhile, North Korea moved to replace its defense minister ahead of the pivotal negotiations, Japan's Asahi Shimbun reported yesterday, citing people that it did not identify.
The comments by Japan's defence chief marked a sharp contrast with his South Korean counterpart, who said there was no reason to doubt the sincerity of North Korean leader Kim Jong-un.
Trump said one thing that could come out of the summit is an agreement formally ending the 1950-53 Korean War, which was concluded only with a truce, not a peace treaty.
The country's foreign ministry said in a statement posted on its official WeChat account that it viewed the meeting between the United States and North Korean leaders as key to achieving denuclearisation and lasting peace on the Korean Peninsula.