A US foreign policy scholar says a Trump presidency would bring uncertainty and instability to the broader Pacific region while a Clinton reign would refocus US efforts.
Sarah Graham of Sydney University's United States Studies Centre said Donald Trump has oscillated a lot on the region during the American election campaign, now in its closing hours.
Dr Graham said if Mr Trump is elected he would need a strong team behind him to help build a vision for the region that governments could be comfortable with.
She said he has questioned the value of America's traditional alliances in the region, particularly Japan.
"He's talked about making allies pay their fair share or walking away.
"This would obviously be a great source of uncertainty and tension in the region given anxiety about China's rise.
"He said that he doesn't really have a problem with Japan or South Korea obtaining nuclear weapons. That would weaken the global nuclear non-proliferation regime and again reverberate regionally but also globally ."
She said there could be chaos and disengagement as a Trump administration settled in, leaving China more latitude to continue its activities in the flashpoint of the South China Sea.
Dr Graham said Hillary Clinton, formerly US Secretary of State, did a lot of the legwork around the US strategic rebalance or "pivot" towards the Asia-Pacific of the last few years.
"She will be aware of some of the concerns that the pivot hasn't been well-implemented and that there wasn't enough follow through and that this has left China a bit of latitude to come in with its actions in the South China Sea and also its economic agreements, so she will be looking to re-establish American credibility."
Dr Graham said Mrs Clinton is not particularly well-liked by China because of her comments on its handling of human rights and because she is associated with the pivot, seen as an effort to contain China.
She said Mrs Clinton would have to manage that relationship carefully, holding firm on the South China Sea but working with China to reset Barack Obama's policy of strategic patience regarding North Korea.
She said Mrs Clinton has the experience to walk a difficult diplomatic tight rope in the region.