China in the last decade has indeed grown really strong. But we must understand that warfare is more than just guns and bombs. The US is highly experienced in evasive warfare. They have a stealth way of manipulating allies and making things go their way. And this is where they cannot be underestimated. Even in the case of an all-out war, there are still great chances that US would win. I mean they still have the greatest military expenditure in the world. Even so by a wide margin.