The conversation between Donald Trump and the president of Taiwan was just a “courtesy call”, vice-president elect Mike Pence said on Sunday as he attempted to damp down a diplomatic firestorm that has the potential to upend US-China relations.

The call between Mr Trump and Tsai Ing-wen was the first such contact since US diplomatic relations were cut in 1979 and has left the world guessing whether the president-elect ignored diplomatic protocol by accident or whether he was signalling that the status of Taiwan would be a central part of his administration’s China strategy.

The phone conversation, which stunned many China-watchers and diplomats in Washington, follows a series of calls with world leaders since the election where Mr Trump has appeared to improvise foreign policy positions, with little input from the government bureaucracy that handles such interactions.