The US military-industrial complex plays a big role in the US economy, selling arms to US and other countries is very profitable. It is the one of the biigest lobbies promoting the "China threat" theory, influencing the Congress to increase military spending. One of the reason why the US Congress passed the Taiwan Relations Act in 1979 was to sell arms to the island, letting the Chinese on both sides of the Strait to kill each other. The US does not give a shit about Taiwan, Japan or any of its "allies". The US learned loong ago that selling arms to "allies and friends" is more profitable than going to war with their enemies. For that reason, the US will stir up trouble between China and its neighbours, but US will not send the navy or army to help them.

China should maintain a credible deterrence.