Japan's Foreign Minister Taro Kono used a visit to Singapore, the current chair of the ASEAN regional bloc, to call for unity in dealing with Pyongyang, a spokesman said.

"We need to maximise pressure on North Korea, to corner North Korea to change its policy by fully implementing the UN Security Council Resolution," said Toshihide Ando, deputy press secretary at Japan's foreign affairs ministry.

"We will continue to work with the United States and South Korea on this issue. But it's important that we should not be blinded by the charm offensive by North Korea," he told reporters at a briefing on Kono's visit.

He said Kono met Singapore Prime Minister Lee Hsien Loong and Foreign Minister Vivian Balakrishnan separately and discussed regional issues, including developments on the Korean Peninsula.

North Korean leader Kim Jong Un has used the Winter Games hosted by South Korea in Pyeongchang to unleash a diplomatic push for his isolated regime.

Kim sent his powerful sister Kim Yo Jong to the Games where she delivered a letter inviting South Korean President Moon Jae-in to a summit. She is the first member of the dynasty to set foot in the South since the Korean War.

North Korea's delegation to the Games also included the country's ceremonial head of state and hundreds of female cheerleaders.

Analysts have said the charm offensive aims to drive a wedge between Seoul and Washington and weaken the world community's resolve to force the regime to abandon atomic weapons.

A day before the Winter Games, the North staged a military parade in Pyongyang to mark the 70th anniversary of its armed forces, putting its intercontinental ballistic missiles on show.