

Trump, who made the proposed border wall a centrepiece of his 2016 campaign, has yet to persuade Congress to appropriate funds to build the barrier. Democrats are united in opposition to the plan and even some of Trump's fellow Republicans have expressed concern about the cost. Meanwhile, Trump's continuing push for the wall -- and his insistence that Mexico will somehow be made to pay for it -- have brought US relations with its southern neighbour to the lowest point in decades.