US President-elect Donald Trump has made a series of notable phone calls in the past few days.
In the words of top diplomats, some of these chats with world leaders have been "animated" while some of the conversations, the call to the Pakistani Prime Minister in particular, have been termed "bizarre".
But on Friday, Trump engaged in perhaps his most high-profile telephonic conversation yet, one that has infuriated China and already forced his transition team and the White House to issue a few clarifications.
According to his transition team, Trump on Friday spoke with Taiwanese President Tsai Ing-wen to discuss "close economic, political and security ties."
The call was significant because it the first such contact with Taiwan by a US president-elect or president since President Jimmy Carter adopted a one-China policy in 1979.
China, which views Taiwan as its province, termed the call a "petty action".
"This is just the Taiwan side engaging in a petty action, and cannot change the 'one China' structure already formed by the international community," China's Foreign Minister, Wang Yi, said.
But Trump, in his signature style, took to Twitter to defend himself.
"The President of Taiwan CALLED ME today to wish me congratulations on winning the Presidency. Thank you!" he wrote.
Hours later there was another tweet.
Interesting how the U.S. sells Taiwan billions of dollars of military equipment but I should not accept a congratulatory call.
— Donald J. Trump (@realDonaldTrump) December 3, 2016
The call comes at a time of worsened Taiwan-China relations since the election of Tsai's pro-independence Democratic Progressive Party (DPP) earlier this year.
Since coming to office this year, Tsai has refused to accept the "One China" concept, prompting Beijing to cut off all official communication with the island's new government.
Tsai's party defeated the Kuomintang (KMT), which had much friendlier ties with Beijing, in a landslide election victory in January.
Tsai told Trump she "hopes the US can continue to support Taiwan in opportunities to participate and contribute to international issues," and called his hard-fought election victory "admirable," her office said in a statement.
Washington is Taiwan's most important political ally and sole arms supplier, despite the lack of formal diplomatic ties.
The White House responded to the call by saying that "longstanding policy" on China and Taiwan has not changed.
"We remain firmly committed to our 'one China' policy," said Ned Price, a national security spokesman for President Barack Obama.
"Our fundamental interest is in peaceful and stable cross-Strait relations."
Also on Friday, Trump invited Philippines leader Rodrigo Duterte to the White House next year during what a Duterte aide said was a "very engaging, animated" phone conversation. Duterte has openly insulted Obama, who cancelled a planned meeting with him in September.
The transition team said that Trump also spoke on Friday to Afghan President Ashraf Ghani and Singapore Prime Minister Lee Hsien Loong.