Its created by its instablity, propaganda, and beligerance... among other things...
If China holds together, it will be a threat to the US in the sense that the US will no longer be the sole power in the West Pacific. China will not be able to take the place of the US as a global power. That is determined by geography. The US is protected by two oceans and two weak semi-friendly countries on its borders. The US is a sea power and by extension, an air power. Examples of this are Great Britain and to some extent Spain.
China on the other hand is a land power. It must protect the local seas but also contend with a long land border with large hostile peoples. It has had many small wars and skirmishes with India and Russia and must be wary of the Turks in central Asia. This requires China to maintain a large army and diverts attention and resources. Other examples of this are France and Germany.
Geography. The United States is blessed in position and resources. If China grows in the West Pacific, we can survive. The US can shift focus to the Americas and Africa. Those areas still have much potential for growth.