CINCINNATI, Ohio --The pugnacious, brawling Donald Trump voters got to know during the presidential campaign is back.
The president-elect returned to his campaign roots Thursday in his first major public appearance since Election Day, holding court in front of thousands of adoring fans - and even announcing a Cabinet pick from the stage.
Washington has pursued a so-called "one China" policy since 1979, when it shifted diplomatic recognition of China from the government in Taiwan to the communist government on the mainland. Under that policy, the U.S. recognizes Beijing as representing China but retains unofficial ties with Taiwan.
A statement from Trump's transition team said he spoke with Taiwanese President Tsai Ing-wen, who offered her congratulations.
"During the discussion, they noted the close economic, political, and security ties ... between Taiwan and the United States. President-elect Trump also congratulated President Tsai on becoming President of Taiwan earlier this year," the statement said.
Trump tweeted later: "The President of Taiwan CALLED ME today to wish me congratulations on winning the Presidency. Thank you!"
A Taiwanese source with direct knowledge of the call confirmed it had taken place. The source requested anonymity to speak about it before an official statement was issued on it from Taipei.
The White House learned of the conversation after it had taken place, said a senior Obama administration official, who requested anonymity because of the sensitive diplomatic relations involved.
China's embassy in Washington did not immediately respond to a request for comment.
Friday's call is the starkest example yet of how Trump has flouted diplomatic conventions since he won the Nov. 8 election. He has apparently undertaken calls with foreign leaders without guidance customarily lent by the State Department, which oversees U.S. diplomacy.
Tsai was democratically elected in January and took office in May. The traditional independence-leaning policies of her party have strained relations with Beijing.
Over the decades, the status of Taiwan has been one of the most sensitive issues in U.S.-China relations. China regards Taiwan as part of its territory to be retaken by force, if necessary, if it seeks independence. It would regard any recognition of a Taiwanese leader as a head of state as unacceptable.
Taiwan split from the Chinese mainland amid civil war in 1949. The U.S. policy acknowledges the Chinese view over sovereignty, but considers Taiwan's status as unsettled.
Although the U.S. does not have formal diplomatic ties with Taiwan, it has close unofficial ties. Taiwan's government has a representative office in Washington and other U.S. cities. The U.S. also has legal commitments to help Taiwan maintain the ability to defend itself.
Taiwan is separated from China by the 110-mile-wide Taiwan Strait. The island counts the U.S. as its most important security partner and source of arms, but it is increasingly outgunned by China.
Ned Price, a spokesman for the White House National Security Council, said Trump's conversation does not signal any change to long-standing U.S. policy on "cross-strait" issues.
"We remain firmly committed to our 'one China' policy," Price said. "Our fundamental interest is in peaceful and stable cross-strait relations."
The NSC stressed that every president has benefited from the "expertise and counsel" of the State Department on matters like this, which suggested that the White House was frustrated by Trump's conversation with the Taiwanese leader.
Still, the White House said Obama remains committed to a smooth transition to the new administration.
Diplomatic protocol dictates that Taiwanese presidents can transit through the U.S. but not visit Washington.
Douglas Paal, who served as head of the American Institute in Taiwan during the George W. Bush administration, said that to his knowledge the call was unprecedented. He said he expected Beijing to issue a verbal warning that there's no space to change the rules over Taiwan relations.