Donald Trump used his first hours back in the White House to begin upending the global order, withdrawing the US from international climate and tax agreements, threatening China with tariffs over social media platform TikTok and flagging punitive duties could be introduced on neighbours Canada and Mexico within days.

As world leaders brace for a tumultuous four years, Mr Trump vowed to “put America first” every single day of his administration, signing a sweeping series of executive orders that keeps faith with his loyal base but sets up likely legal challenges to the limits of his presidential power.