Some of the campaign rhetoric may have troubled the United States' long-time ally Japan, but Tokyo's response is that it will work with whoever is the new US president.

The goal is to "further strengthen Japan-US relations going forward", Prime Minister Shinzo Abe said earlier this month.

Regional Revitalisation Minister Shigeru Ishiba told a forum in Washington recently that while the comments of a presidential candidate caused "a lot of concern", he was sure "the proper policies will be formulated with an understanding of the nature of the alliance and the international environment".

Presumptive Republican nominee Donald Trump, who has been touting an "America First" foreign policy, wants Japan and South Korea to pay more for defence arrangements. He also suggested they develop their own nuclear weapons - an unthinkable idea to the only country to be attacked by atomic bombs.

Such views are "a betrayal of trust (and) antithetical to the foundations of bilateral relations", Professor Jeffrey Kingston, director of Asian studies at Japan's Temple University, told The Sunday Times.

But he noted that Mr Trump's views on security "dovetail with the wish list of hawkish conservatives" who are eager to see Japan expand its security posture and take more responsibility for national security. This is because the comments show that "in a time of need, the US may be an unreliable ally".

In comparison, Democratic front runner Hillary Clinton is "admired and represents the responsible adult in the room", Prof Kingston added, given her previous job as secretary of state.

Walter Sim