Close attention will be paid to Taiwan leader Tsai Ing-wen's transit via the United States when she travels to Guatemala in early January, for it will shed light on what direction Sino-US relations will take when Donald Trump enters the White House.

Despite Beijing's opposition, the US insists it is a "long-standing practice" since it has given the nod to such transits by leaders of the island many times before.

However, Tsai's transit is taking place soon after she and Trump held a phone conversation, breaking with decades of precedent.