US President-elect Donald Trump's comments - that he may not abide by the One-China Policy - have led to concerns of how China-US ties will fare under his administration. The outgoing US President is also urging caution on his successor. CCTV correspondent Jim Spellman has the details from Washington DC.

U.S. President Barack Obama attends his final news conference of the year in White House in Washington D.C., the United States, Dec. 16, 2016. U.S. President Barack Obama said on Friday no other bilateral relationship carries more significance than U.S.-China relationship, and if the U.S.-China relation breaks down, everyone becomes worse off. (Xinhua/Yin Bogu)

U.S. President-Elect Donald Trump's comments that his administration would not necessarily be bound by the one-China policy have drawn criticism from around the world.

And now the current U.S. President is sending a warning to his successor.

"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 are because the Chinese will not treat that the way they will treat some other issues," Obama said.

China's Foreign Ministry reacted forcefully to Trump's comments.  

"We urge the new US administration and its leader to fully understand the highly sensitive Taiwan issue, continue to adhere to the one-China policy and principles of the three joint communiques guiding Sino-U.S. relations, and handle the Taiwan issue cautiously and properly so that the bigger picture of China-U.S. relations would not suffer from any major disruption and damage," said Chinese Foreign Ministry Spokesman Geng Shuang.

And now some of the strongest U.S. allies are weighing in.

"We still stand by a one-China policy and we will not change our stance," said German Chancellor Angela Merkel.

"You don't talk to a partner like that, because China is a big partner. When China feels questioned on its unity, that's not exactly very clever," said French Foreign Minister Jean-marc Ayrault.

Some analysts say it would be disastrous for the U.S. if Trump tries to ignore the one-China policy.

"Abandoning the one-China principle would affect the U.S.'s entire relations with China. The interests of the US in its relations with China by far outweigh those it has in its relations with Taiwan," said Wu Xinbo, Executive Inst. for Int'l Studies, Fudan University.

President Obama says China and the US can disagree over issues in a constructive way, but respecting the one-China policy is vital to the future of U.S. relations with China.

"This goes to the core of how they see themselves and their reaction on this issue could end up being very significant. That doesn't mean that you have to adhere to everything that's been done in the past. It does mean you got to think it through and have planned for potential reactions that they may engage in," Obama said.