President Donald Trump’s latest trade fight with Canada has a faraway force at its center: China.As Washington presses Ottawa to do more to prevent Chinese steel, aluminum and other goods from reaching the U.S. market through North American supply chains, Canada is pursuing renewed economic ties with Beijing, adding a fresh complication to already tense trade talks.At the heart of the fight is transshipment — routing goods through an intermediary country, sometimes after limited processing, before they reach their final market. U.S. officials fear steel and aluminum made in China or elsewhere...