Donald Trump has broken with decades of US foreign policy by speaking on the phone with Taiwanese President Tsai Ing-wen, the president-elect's biggest move on the world stage since winning the election last month.

The call, which China labelled "just a small trick" by Taiwan, was the first such contact with Taiwan since President Jimmy Carter adopted a one-China policy in 1979.

A foreign policy novice, Mr Trump's early moves on international relations and national security are being closely watched by both US allies and adversaries.

Here are the ways the president-elect has made waves with his handling of foreign affairs since his election on November 8.

'Historic' call with Taiwan's president

It was not known whether Mr Trump's "historic" call with the Taiwanese president was a deliberate shift in the "one-China" policy or a naive mistake. Either way, it riled China, which views Taiwan as a renegade province.

Calling it "just a small trick by Taiwan", Beijing said the "one-China policy" was the cornerstone of US-China relations and that it hoped that foundation would not be "interfered with or damaged".

Mr Trump's transition team issued a statement saying the two had noted that "close economic, political and security ties exist between Taiwan and the United States".