China has urged the US to abide by the "one China" principle ahead of the transfer of power from China-friendly Ma Ying-jeou to pro-independence Tsai Ing-wen in Taiwan later this week.
Ms Tsai and her Democratic Progressive Party (DPP) will take over the reins on Friday (May 20), ending eight years of rule by Mr Ma and his Kuomintang during which cross-strait ties, especially in trade and tourism, improved dramatically.
Chinese Foreign Minister Wang Yi told his US counterpart John Kerry on Monday that China hopes the United States will abide by the "one-China" policy, the three China-US joint communiques that form the bedrock of bilateral ties, and properly handle the Taiwan issue, Xinhua news agency reported.
Mr Wang was speaking during a phone conversation with Mr Kerry at the latter's invitation, Xinhua reported.
Mr Kerry said the United States attaches great importance to its relations with China, the report said.
Washington has not changed and will not change its stance on the Taiwan issue, and does not support Taiwan independence in any forms, he said.
Mr Wang's reminder was just one of many moves seen as being designed to keep a post-Ma Taiwan in check.
Ms Tsai, whose party platform calls for formal independence for Taiwan, has not publicly accepted the 1992 consensus, a tacit agreement between Beijing and Taipei in 1992 that there is one China, with each side having its own interpretation of what this means.
She won Taiwan's elections in January by a landslide largely on the back of young Taiwanese's frustration with the island's stagnant economy and perceived lack of an independent identity under China shadow.
The US switched diplomatic recognition from Taiwan to China in 1979 but is bound under its Taiwan Relations Act to defend the island if it is attacked.
Mr Wang and Mr Kerry also spoke about the Syrian civil war during their phone call, Xinhua said. Mr Wang said China supports US-led efforts towards a comprehensive ceasefire in the war-stricken country and will continue to play a "constructive role" in the crisis.