The foreign ministers of Japan, the United States and South Korea on Sunday reaffirmed their unity in urging North Korea to denuclearize as promised, despite Pyongyang accusing Washington of making unilateral and "gangster-like" demands.

The ministers stressed the need to call on North Korea to take concrete steps toward denuclearization and to keep existing U.N. economic sanctions in place.

"We were able to reaffirm our unwavering commitment to the continued strengthening of our trilateral cooperation toward the common goal of North Korea's complete, verifiable and irreversible dismantlement" of all nuclear weapons and missiles, Japanese Foreign Minister Taro Kono told a joint press conference.

(From left, Mike Pompeo, Japan FM Taro Kono and S. Korea FM Kang Kyung Wha)

The second trilateral meeting in less than a month followed U.S. Secretary of State Mike Pompeo's visit to Pyongyang on Friday and Saturday where he tried to work out the specifics of denuclearization with senior North Korean officials.

Washington and Pyongyang's different take on the outcome of the latest meeting pointed to discord as North Korea accused the United States of making unilateral and "gangster-like" demands. Still, Pompeo dismissed North Korea's accusation.

"I know actually what precisely took place. When we spoke to them about the scope of denuclearization, they did not push back," Pompeo told the press conference.

"If those requests were gangster-like, the world is a gangster because there was a unanimous decision at the U.N. Security Council about what needs to be achieved," Pompeo said.

Kono and South Korean Foreign Minister Kang Kyung Wha received an update on what progress has been made since the June 12 summit in Singapore in which North Korean leader Kim Jong Un promised U.S. President Donald Trump to work toward denuclearizing the Korean Peninsula.

Skepticism has grown over how and whether North Korea will dismantle its nuclear weapons program amid U.S. media reports that the country has continued to develop nuclear facilities.

Pompeo said his meeting with Kim Yong Chol, a vice chairman of the Central Committee of the Workers' Party of Korea, produced progress and they talked "a great deal" about a potential timeline for the denuclearization process. But he added there remains work to be done.

Pompeo's visit to North Korea has led to the launch of working groups to deal with details such as verification.

Earlier in the day, Prime Minister Shinzo Abe stressed the importance of a comprehensive resolution of issues related to North Korea during his meeting with Pompeo.

"The settlement of outstanding issues surrounding North Korea, including nuclear, missile and abduction, will be extremely important to Japan, and that will also be extremely important for regional peace and stability," Abe said at the outset of the talks.

Abe has made it a priority to resolve the issue of Japanese nationals abducted by North Korea in the 1970s and 1980s and has expressed a willingness to hold direct talks with North Korea even as questions remain over what a potential summit will yield.

Trump raised the issue when he met with Kim in Singapore and Pompeo also talked about it during his latest visit to Pyongyang.

"It's part of our discussions each and every time we interact with our North Korean counterparts," Pompeo told the press conference with Kono and South Korea's Kang, who also said the issue is of concern to Seoul.

Apart from the trilateral meeting, Kono held separate talks with Pompeo and Kang.

Last month, Pompeo briefed Kono and Kang in South Korea on the outcome of the Trump-Kim summit. But he also had to assuage anxious Asian allies after Trump said he would be stopping U.S.-South Korean military exercises.