What will Trump presidency mean for Asia and China’s regional role?

Pivot or not, the future of the US policy of engagement with Asia is likely to be a defining feature of a Donald Trump presidency, especially after the US president-elect released a video on Monday in which he pledged to withdraw from a major regional trade accord on his first day in office.

Turning the worst nightmare of America’s regional allies into reality, the 70-year-old real estate mogul’s surprise election victory threatens to dismantle US President Barack Obama’s Asia policy legacy and put decades-old US alliances in the region in doubt.

WATCH: US president-elect Trump announces he will cancel the TPP agreement

Some diplomatic pundits even say an isolationist foreign policy under Trump, known for his showman style and brash and blunt personality, might become a turning point for America’s leadership of a chaotic world – with an increasingly assertive China in mind as a successor.

Although America’s president-elect has yet to unveil his foreign policy line-up or release any policy road map, observers warn that Asian nations should expect a bumpy ride ahead, with post-election chaos and uncertainty likely to reign in Washington in the coming weeks, if not months.

During his campaign, Trump frequently criticised Obama’s Asia policy, mused about the possibility of abandoning America’s long-standing promise to defend key regional allies such as Japan and South Korea, and challenged various “job-killing” multilateral and bilateral free-trade deals, including the 12-nation Trans-Pacific Partnership (TPP) that the US signed early this year but has yet to ratify.

In Monday’s video, Trump described the TPP as a “potential disaster for our country” and said he would instead negotiate bilateral trade deals that would “bring jobs and industry back onto American shores”.