President-elect Donald Trump broke with decades of cautious U.S. diplomacy to speak with the president of Taiwan, at the risk of provoking a serious rift with China.
S President-elect Donald Trump
V broke with
O (decades of cautious) U.S. diplomacy
V to speak
with the president →どんなof Taiwan
補足at the risk
O （a serious） rift →どんなwith China.