"The idea of ‘one China’ is at the heart of their conception as a nation," Obama told reporters Friday. "If you are going to upend this understanding, you have to have thought through what the consequences are. [Chinese] reaction on this issue could end up being very significant."
The outgoing president stressed the importance of stable relations between Washington and Beijing and said disputes would disadvantage both countries.
Obama added that he has advised Trump to assemble his administration first, before interacting with foreign government officials.
At the same time, Obama conceded that US foreign policy should be "subject to fresh eyes."
Concern over US relations with China and Taiwan has risen since Trump became the first US president or president-elect to speak with a Taiwanese leader in an official capacity since 1979. Trump and Taiwanese President Tsai Ing-wen spoke by phone on December 2, with the incoming president later insisting on Twitter that he hadn’t initiated the call in which Tsai congratulated him on his November 8 election victory.