【明報專訊】2017 is bound to prove a year of Sino-US chess playing. On that side of the Pacific, US president-elect Donald Trump talked impertinently about China when he electioneered. After he had won the election, he talked with Taiwan President Tsai Eng-wen over the phone, and threatened to dump the "one China" policy to compel Beijing to give ground. He smells strongly of gunpowder though he has yet to be sworn in. On this side of the Pacific, Xi Jinping, who is hexin (core) of the Chinese leadership, said at a Politburo "democratic life" meeting whose theme was supposed to be "stepping up intra-Party supervision", "In safeguarding the country's core interests, we must dare to give tit for tat, we must not bow to difficulties or shrink from challenges, and we must never barter away principles or swallow any bitter fruit of damaging the Chinese nation's fundamental interests under duress." Unlike Trump, he has named no names. However, the message those remarks convey is exceedingly clear.