"The idea of One China is at the heart of their conception as a nation and so if you are going to upend this understanding, you have to have thought through what the consequences because the Chinese will not treat that the way they will treat some other issues.
"They will not even treat it the way they issues around the South China Sea, where we have had a lot of tensions. This goes to the core of how they see themselves," Obama told reporters at a White House news conference yesterday.
He was responding to a question on recent phone conversation between Trump and the Taiwanese President and the President-elect questioning the relevance of One China Policy.
At the same time, he indicated that Trump could bring in some freshness in foreign policy.
Also Read
"I think all of our foreign policy should be subject to fresh eyes. I am very proud of the work I have done. I think I am a better president now than when I started. But you know, if you are here for eight years in the bubble, you start seeing things a certain way and you benefit from, the democracy benefits, America benefits from some new perspectives," he said.
Given the importance of the relationship between the US and China and how much is at stake in terms of the world economy, national security, the US presence in the Asia- Pacific, China's increasing role in global affairs, there is probably no bilateral ties that carries more significance.
And where there is also the potential if that relationship breaks down or goes into full conflict mode that everybody is worse off, he said.
"Since there is only one president at a time, my advice to him has been that before he starts having a lot of interactions with foreign governments other than the usual courtesy calls, that he should want to have his full team in place, that he should want his team to be fully briefed on what is gone on in the past.
"And where the potential pitfalls may be, where the opportunities are, what we have learned from eight years of experience so that as he is then maybe taking foreign policy in a new direction, he has got all the information to make good decisions, and by the way, that all of government is moving at the same time and singing from the same hymnal," Obama said.
Taiwan operates differently than mainland China does. China views Taiwan as part of China, but recognises that it has to approach Taiwan as an entity that has its own ways of doing things, Obama said.
"The Taiwanese have agreed that as long as they are able to continue to function with some agree of autonomy, that they won't charge forward and declare independence.