Japan's Prime Minister Shinzo Abe said he had an in-depth conversation with Chinese Premier Li Keqiang on the issue.
During the bilateral talks held on the sideline of the three-way summit that also involved Japan, South Korean President Moon Jae In emphasized the importance of seeing a "success" in the upcoming talks between USA and North Korean leaders on nuclear issues.
Abe said the timing of easing or removing sanctions on the Democratic People's Republic of Korea (DPRK) is important and concrete measures should be taken after the DPRK closes its nuclear test site.
The comments came shortly after the heads of the two neighboring nations held inter-Korean summit and pledged to achieve complete denuclearization of the Korean Peninsula.
East Asian powers on Wednesday threw their weight behind breakneck diplomacy to rid North Korea of nuclear weapons, setting aside their differences on the process to endorse an intra-Korean deal.
Kim reiterated his commitment to the denuclearization of the Korean peninsula during his meeting with Xi, and the Chinese leader later in a phone call urged Trump to take the North Korean leader's security concerns into consideration.
Chinese President Xi Jinping met Kim Jong Un in China for the second time in six weeks on Tuesday and later spoke with Donald Trump, in an intensifying whirlwind of diplomacy as the North Korean and United States leaders prepare for a historic summit.
Earlier in the month, South Korean police clashed with labor group members trying to put up a statue symbolizing Korean laborers who were forcibly taken to Japan during its colonial rule of the Korean Peninsula between 1910 and 1945.
The leaders discussed Pyongyang's nuclear weapons programme and supported free trade.
In a public ceremony after their meeting, Abe and Li oversaw the signing of a pact to set up a hotline for senior defense officials to communicate during incidents involving each others' naval vessels or military aircraft.
Before a meeting as part of Li's state visit to Japan - the first such visit by a Chinese premier since 2010 - Abe said he wanted to raise bilateral ties to a new level and visit China later this year.
In remarks to journalists, both men hailed warming ties between their countries with Li saying better relations between them was contributing to global stability and development.