Unless we’re in a war, I don’t tend to see countries as “enemies”. Not even North Korea, Iran and other actually hostile nations are real enemies at this time to the USA or to the West in general. We never fought a war against the USSR / Russia, either. They’ve never been “an enemy”. I hope that we never fight a war against China.
However, China does seem to have hegemony on its mind. It has already taken over the formerly independent Mongolia (anyone even remember Mongolia any more?) and Tibet. We haven’t quite forgotten about Tibet yet, but China plays the long game, and they know that we will eventually forget. In that same spirit of “playing the long game”, they are staking claims to uninhabited islands in the South China Sea so that they can make great “territorial waters” claims, which would enable them to control fishing, undersea mining and oil exploration / drilling, and eventually shipping lanes as well. They have territorial disputes with India that could help them to eventually take over Nepal, Bhutan and even the “Seven Sisters” region of Northeast India (the section that is only connected to the main continental body by a very narrow isthmus).
Since the dissolution of the USSR there are a lot of other landlocked nations in Central Asia that will eventually be ripe for the plucking, too. China has time to wait.
China has for thousands of years attempted to be – and at times has been – an imperial power in the way that Japan’s rulers wanted it to be for a few short years in the last century. Japan seems to have been cured of its obsession with empire. China has not.
I still don’t consider the nation of China to be “an enemy”, but it would be historically foolish to ignore their ambition. And little imagination is required to perceive these realities.