Japan sees joint military drills between the United States and South Korea as a vital security deterrent in North-east Asia, Foreign Minister Taro Kono said in Seoul yesterday.
Meanwhile, Japanese diplomats were also working yesterday to realise a summit between Prime Minister Shinzo Abe and North Korean leader Kim Jong Un, possibly in the coming months.
Mr Kono told a news conference, alongside US Secretary of State Mike Pompeo and South Korean counterpart Kang Kyung Wha, that while precise details of the halt in joint war games are to be ironed out between the US and South Korea, "we understand that any pause in exercise is contingent upon DPRK action towards denuclearisation".
DPRK, or Democratic People's Republic of Korea, is North Korea's official name.
The trilateral talks involving the US and its two Asian security allies followed Tuesday's historic summit in Singapore between US President Donald Trump and Mr Kim that has been criticised as more style than substance for its vague joint declaration.
Keio University expert Yasushi Watanabe told The Straits Times that the abrupt halt of joint military drills - seemingly without first informing South Korea - has raised concerns in Japan that the US might some day unilaterally wind down its security commitments in the region.
This will not just be a win for North Korea, but also for China, he said.
"Trump's decision is exactly what China has been demanding, a freeze-for-freeze," he said.
"There is plenty of domestic concerns that the halt of exercises would also lead to further burdens on the part of Japan," he added.
The Yomiuri Shimbun said Mr Abe may visit Pyongyang in August for talks with Mr Kim, though the meeting could take place in Russia in September on the sidelines of an annual economic forum.
Russian President Vladimir Putin yesterday extended an invitation to Mr Kim to visit Russia.
Mr Kim, whose official title is Chairman of the State Affairs Commission, had himself told Mr Trump that he was open to the idea of meeting Mr Abe, local media quoted Japanese government officials as saying.
Kyodo News reported yesterday that Japanese and North Korean officials have made informal contact at an international conference in Mongolia, where a senior diplomat conveyed Tokyo's position on resolving the longstanding abduction issue with the North.
This refers to the kidnapping of Japanese citizens by North Korean agents in the 1970s and 1980s.
Dr Watanabe said that as the abduction issue was a legacy from the past - when Mr Kim's grandfather and his father were in power - it "might be easier for Kim to face this issue more directly and more positively".
Cabinet spokesman Yoshihide Suga said yesterday that he hopes a summit with the North could lead to the eventual normalisation of ties between both countries.